Your experience points and the number required for the next level are listed in the inventory window. There are 2 parts to activate skills; first you must find a book or teacher to learn them (you will also start off with some skills available depending on your choice of skill class when creating the game), and then you must open the skill window to assign skill points.
If you have unassigned stat or skill points, the inventory or skill icons under the portraits will change to a red arrow.
Some skills are passive, so are always working (Identify, weapon expertise when you have the required weapon class equipped), some work by right clicking on an item in your inventory (Repair, Alchemy) and active skills must be selected as your primary/secondary action and triggered with a mouse click.
