Gandi: https://www.gandi.net/domain/transfer
1and1: http://order.1and1.com/xml/order/DomaininfoMove
NameCheap: http://community.namecheap.com/blog/2011/03/30/elephants/
Basically go to any registrars home page and either search for "Transfer" on the page itself or in their search box if provided. They will all offer it together with easy how to steps - and I am sure their support team will help as well. They want your business and will make it as easy as possible.
I've been using namecheap for a couple of years, and I'm very happy with them.
We had a bit of trouble with them on credit card billing... Also, we found it hard to use their interface to change configuration settings.
I paid and will avoid 1and1 for the rest of my life.
Another one to avoid like the plague imho is dotster - lost a domain via dotster, even though my payment was accepted and then returned a week later. Domain briefly showed up with whois information of the CEO, and then it changed.