WotLK How do I connect?

Hello and welcome. I assume you made an account already, the next step is to download the client you need. Press the "DOWNLOAD" button in the top of the website and choose the client. They're all different expansions so choose the one you wish to play. When you download it, start the game using the "Wow.exe" file. When it opens you will see two empty fields. In the first field you type in the username (from the account you made on the website earlier) , NOT the e-mail. You type in your password and there you go! Choose a realm and start playing. Goodluck.