go to ebay.com
Sign in under 'my ebay' (near top)
look at stuff (can put item you would like to see where it says 'search'
when you like something, click on it
click 'buy it now' if it's a 'buy it now' listing; Follow prompts to pay for it.
if it's an 'auction' place a bid where it says 'place bid'. Note the ending time and check it in your 'my ebay' under 'bids' to see if you won. If you did, follow prompts to pay for it.