i just made a world of warcraft account and I dont know how to log in to the actual game. Can anyone help?

I first got world of warcraft the regular for a demo. Then I wanted it so i bought it. Then i bought the burning crusade and downloaded it. This was all online at their site. Now my computer crashed is there a way I can download them again without paying a second time.

I got my son World Of Warcraft its a battle chest? but it has 2 games world of warcraft and an expansion called the burning crusaide. and he said he wants to get the lich king expansion also.. what do these expansions do? and are they different games or does it jsut add stuff to the original game like new places to go and stuff?

I want to start a raid in world of Warcraft but I dont really understand how to do it and what the benefits of doing it are. Ive pretty much just played the game by myself and never really done many of the dungeons or anything like that. I have a level 65 warrior if that helps at all. If anyone can tell me how to do it I would appreciate it.

I am just now picking up WoW again before Lich King, and I had deleted all of the mods that I used to play with. But the ones I did play with, they were tricky to install, and a lot of the times didn’t show up in game.

Are there any other Mac users that play world of warcraft and would be able to help me out with my dilemma? As well as if anyone has any suggestions as to what mods they think I should get.