My destruction skill is at 24 and i want to raise it, so i cast fireballs and such, but it doesnt seem to increase that red status bar thingy..

You have to actually cause harm to something that can be harmed... monsters, NPCs, yourself...

In order to increase the skill, it has to affect something when used. Casting fireballs at rocks or into the sky won't do anything for it. You have to hit something living (or undead). If you have a summon spell, summon something and shoot it with fireballs.

Edit: Ninja'd by UnclePain.

Ah, thanks. Thought id ran into a bug..

Also if you have access to a spell-making altar you can make a self-damaging destruction spell, like drain fatigue 1 point or something. But I advice against playing that way, you should level destruction the normal way so it won′t feel like a grind.