H1B Visa Renewal

My H1B visa will expire this September, and therefore need to renew it. I went to INS\' website, and did not find any official documens in regards to H1B visa renewal. For instance, the paperwork my employer needs to prepare.

Can someone tell me the link of official documents on H1B visa renewal?

I am really looking forward to hearing from you.

Many thanks,
Happy CC