I won't say what you are "supposed to" do since you can play however you'd like, but I will say that the norm (in T4s at least) is for the warrior to go full damage (normally some mix of berserker and assassin's) and for the group to have a dedicated healer. That being said, it is entirely possible to do fractals without a dedicated healer. Without more specific details on what you are having trouble with, I can only make assumptions. One possible issue is that you are taking a lot of unnecessary damage. A way to avoid this is by getting a better understanding of the mechanics for each fractal (maybe through practice or watching video guides on youtube.) I see a lot of people that get hit by the same mechanics that are easily avoidable when I do fractals. There are several fractals with one shot mechanics that some people fail to avoid. I also see people that stand in places they shouldn't stand (like giant red circles for example). One possible issue is that your team does not stack well. Stacking does (at least) two useful things. One, it helps with boon and support sharing. If your team is altogether, boons and healings are easier to distribute amongst the group members. Two, it (normally) means that monsters will come to you, you will be able to hit more of them at once and they will die faster (meaning they have less time to hurt you). Another possible issue (somewhat related to the stacking) is that your groups DPS is not very high, which means mobs have more time to kill you. Either way, if I were you I would try to find groups with dedicated healers, I would drop the soldier's gear and go full berserker, and I would try to see what damage I am taking that I can avoid. Warrior is one of the more naturally tanky classes due to heavy armor and high health pool, so ideally a warrior would not have too much trouble surviving in a good group. As far as building tankier goes, I would personally recommend against that. Normally tankier builds means that you will survive longer but do less damage, which in the long run will only prolong the inevitable wipe. Building tankier could also potentially reinforce any bad habits you have. (just as a note, I am not saying you can avoid ALL damage in fractals, but it is definitely possible to avoid enough damage to survive. To reinforce that point, here is a video of a player soloing a 99CM boss without taking any damage. Obviously this player is very experienced and practiced quite a bit, but the video is just to illustrate the possibilities. )
Either way, good luck. If you have a more specific question please post it.