If you're from either Bastok or Sandy, you need to go to Valkurm Dunes (which is half-way between both cities). Put up your seek-party flag and wait for an invite.
You'll start off by fighting lizzards in the extreme south/east corner of the dunes (near the zone to the Konn. Highlands.)
You'll want a map of the region before you go. Since you are a "War", you will most likely be the party's "tank". That means it's your job to provoke the monster, build 'hate' and keep the mob focused on attacking you (no, I'm not kidding - that's what tanks do and that's the War's job). The party's healer (Whm) will keep curing you. This will make the mob 'hate' the Whm. If it goes after the Whm, provoke it as fast you can - do not let the mob attack the Whm (dead Whm = dead everybody else in the party). If another player provokes the mob away, then provoke it back as soon as you are allowed to (one voke each 30 seconds).
If someone else in the party is the main tank (if you have a Pld, for example) then you will just be the backup tank. This means you keep your provoke at the ready and if they start taking too much damage (get into the Red at any time - or they get into the Orange and it doesn't look like the Whm can cure them), you voke the mob. A Pld has some MP to cure themselves but they get interrupted if they are the focus of the mobs hate. You're buying them some time to self-cure - they'll provoke the mob back as soon as they can.
BTW - Ninja would also be main tank -- except Ninja needs the Ninjitsu "Utsusemi" which they can't have until lvl 13 at the earliest. So at level 10 you don't need to worry about it.
OTHERWISE... go to Konn Highlands (if you are from Bastok) or La Theine Plateau (if you are from Sandy) and solo mobs until you get to lvl 11 or 12.
The game is gonna start getting much more interesting now that you are at a lvl where you can party.
BTW - while in the Valkurm Dunes, keep in mind a few dangers:
1 - all goblins will aggro you -- and at lvl 10, all gobs will also win. At lvl 12 you can start taking on *some* gobs AS A PARTY - but never solo. So stay well clear of the gobs.
2 - most bats will also aggro you -- this isn't as much trouble as the gobs, but if you are solo just be very careful. There are bats in the tunnel that you need to pass through and you might pickup a few "friends" while you're trying to pass through. If this happens while you are solo, run all the way south (from that tunnel) and zone to Konn. Highlands to lose the bats. If it happens in a party, stand and fight because the party can pretty much take care of the bats -- they aren't so difficult.
3 - NIGHT: At night time hours (18:00-4:00) you will get Ghouls (skeletons) and Bogys (ghosts). In the mid teens (say 15-16) a party might be able to take down the Ghouls, but NOT THE BOGYS. STAY WELL AWAY.
Sub-job quest:
At lvl 18 you are allowed to do the "sub-job" quest. The NPC is on the western edge of the beach in the port town of Selbina (which is in the middle of the Valkrum Dunes). He will tell you the "secret" to getting a subjob *if* you bring him 3 items. I'm telling you this because you can start collecting the items now.
After you fight so many lizzys that the XP isn't paying off, it's time to take on Snippers. At first you should fight snippers on the eastern cliff area over-looking the beach. These snips tend to be weaker. But later you can go right down onto the beach and take on those snippers (which tend to be a little tougher). The snippers drop 'Crab Apron' - which is one of the 3 items you need. It's an "ex" item which means you can buy/sell/trade it -- it's ONLY use is to help you do the sub-job quest.
If everybody else in your party already has a sub-job then they wont want the crab apron. You need to 'lot' for it. Select yourself (usually hit the F7 key), click up the menu, then select "treasure". Select the "Crab Apron" and pick "Lot" (to cast a lot). The computer picks a random number between 0 and 999 -- the person with the highest number wins it). Others who already have it will do the same except they'll pick "Pass" (instead of "lot") - which means they don't want it. There's an ettiquette to casting lots. You should ONLY ever cast lots of items you NEED -- not on items you WANT. Everyone understands you NEED the Crab Apron and nobody will be upset. But if you start casting lots on everything else (Wind Crystals, for example) then people are gonna get upset with you. Just let the game randomly distribute those items.
The other two items you need are the Damselfly Worm (which you get from fighting Damselflys). If you can take on the snippers on the beach, then you can also take on Damselflys. They do use "poison" quite a bit -- so hopefully your mages have "poisona" to remove it.
The final item you need is the "Magiked Skull" You get those from fighting Ghouls. This is the trickiest one to get. If you are easily taking on Snips and Damselflys, then odds are your party can take Ghouls too... except they only come out at night (18:00 - 4:00) and it's a rare drop. Most people don't actually get their skull in the Dunes. There's a mine in Konn. that's LOADED with these Ghouls -- but if you go in there you'll get ripped to shreds. You need "high-level" (it's all relative folks) to go in there. Some with a lvl of say 28 or more can probably fetch a skull for you. Obviously the higher they are, the easier it will be for them. The ghouls aren't actually that tough as to require such a high level -- the problem is they are found in "clumps" and they link like crazy. So you think you're taking on one and the next thing you know you're taking on 7 -- with a hound or two thrown in for good measure.
When you have all 3 items and are at least lvl 18, go talk to the NPC on the west edge of the beach to get the quest assigned, then trade him the 3 items he wants (ONE at a time - he doesn't expect you to come back with everything all at once - and the order doesn't matter).