I can't be the only one that doesn't understand how this works. You level up in Acrobatics for running? Running? Same for jumping around. It seems more than a little broken.
There are 2 types of skill in oblivion. Primary and secondary skills. Primary skills when leveled up will contribute to your character level, while secondary skills when leveled will determine how much youll level up an attribute.
It might look confusing now but it isnt, and it isnt that important if your just playing.
Whenever you apply a skill, you gain experience with it. At a certain point, you've gained so much experience in that skill, that it levels up.
If all of your core skills have leveled up (you have chosen what your core skills are at the start of the game), your character as a whole levels up.
Skills like Armor get experience whenever you block, Sneak increases while you sneak, Acrobatics increases when you jump, etc.