Welcome aboard.
First and foremost I suggest you observe how abstract the 4 edition rules are. "Power" is a generic term for everything excepcional the characters do, either magical or not. Same goes with the HP system, meaning damage is more tham just bruises, and include fatigue, magical energies, divine intervention, luck, battle awareness and so on.
Using the basic set of rules (not Essentials) your character starts at first level with:
* Attack Powers*
- At-will attack powers, with you can use freely, usually they spend standard actions in combat and most characters start the game with 2 of those.
- Encounter attack powers are more powerfull. Your character can do something exceptional either once per fight, or once every 5 minutes (it's an aproximation, an abstraction, not exact science). Most characters start the game with one encounter attack power.
- Daily attack power is your most powerfull (usually most damaging) attack, and can be used once between extender rests (ok, once a day). You start the game with one of these. In the case of wardens, they have special dailies that transforms your character into something else (like a tree-like creature, for example), but they only charges the stats written there - the new form never has implicit game advantages.
Players Handbook has a table with how many attack powers any character have per level. Most start with 2/1/1 of the above.
* Utility Powers*
There are other powers that are not attack powers, the utility ones. You grab the first one usually at second level, so don't worry about them at the momment.
If you are a player from previous editions you will see that 4th edition is more advanced, but it's also very simple in many aspects. Most of the rules are condensed in the character sheets themselves and the "conditions" are cleary defined in the rules.
Allow me to give you 1 piece of advice on conditions: read the descriptions carefully and don't make any assumptions nor game table house rules on the fly. Take "blinded" for example - if your character is blinded for 1 round (6 seconds), it could be just sun flare, sand in the eyes, something like that, your character is not really blind in the literal sense of the term. Same goes for restrained, you can still attack, and so on. Conditions are just game terms, ok?
Best thing about the 4th edition is that it leveled the playfield, and streamlined a lot of the rules. If you have a power that can knock prone, for example, you can actually knock big bad 4-legged monsters prone. For example, you hit a dragon's knee and if he is prone may just mean he is off balance, ok? Nevertless he will grant you combat advantage, will not be able to move much and so on...
Imagination is the key!
Regards, Sage.
