You don't necessarily need to tank really on WAR, because it has Provoke and has some good melee damage and defence you end up shoehorned into that role more often than not in the dunes. If you're honest with your parties and say "yo I'm actually new to FFXI" they'll give you a hand, not just with leveling but also with subjob quest, unlocking whatever advanced jobs you might want to play, and generally whatever else you might want to do.