The skills window is accessed by pressing '''F2'''. This will display all your skills and how good you are at it. More skills will be available as you uncover them. By pressing the plus, [+] you can expand the skill tree.
Hovering the mouse over any of the skills will display you a more detailed digit numberprecise value.
=== Inventory window ===
Aah, the good stuff. Press '''F3''' to bring your inventory window up.