Click on the link within the text message you received to login you in automatically to your own personal bidding center.
You can click "View All" or "Browse by Category" - you can even add items to you're own "watch list"
Click "Bid" on the items you'd like to bid on - you'll be asked to confirm on a pop-up screen. You can manually enter any amount that is greater than the "next bid"
You're encouraged to set a "Max Bid" so you don't risk getting outbid on an item you've been eyeing! The auction software will automatically raise your bid by a predetermined increment until your max bid has been met or the auction ends.
You can also click "Buy Now" on certain items to purchase the item outright.