Skills - Skills determine what equipment / ships you can use or how good you are at using them (bonuses to various attributes if you have better skills). One nice thing about Eve Online is that skills train in real-time, even if you're not logged on. So if you're busy, login for 30 sec, start training your next skill, then log back off.

Skills have tiers (which determine how long it takes to train additional levels of the skill) and levels (how good you are). For the most part, you can completely ignore the tier values. Worry more about getting your basic skills up to Level II.

Some skills have other skills as prerequisites. In order to learn a more advanced skill, you usually have to learned the previous skill to a particular level (or better). If that sounds confusing, fire up EveMon and look at the skills under the "Learning" category. You'll see how skill dependencies work.

The hard part is getting enough skills to do what you want in a frigate (low-level ship).