when i try to start fallout 2 it gives a message about my resolution.
how to fix this?

If it still plays then no problem, if not you probably need to lower your resolution.

You can also get some patches made for the game. I use http://falloutmods.wikia.com/wiki/Sfall and http://falloutmods.wikia.com/wiki/Fallout2_High_Resolution_Patch nowadays, so I can get the game windowed with higher resolution.

I haven't really had problems with Fallout 2 screen wise. I usually just do Ctrl, Alt, Delete and back out of that screen and it looks fine.

BTW is there any mod that allows you to give you character gear? something like console comand.

There are char & inventory editors if that's what you mean. But I wouldn't recommend cheating, takes the fun away. I only use them to test certain scenarios or for debugging like unsolvable quests. Doesn't happen often, though.