julia, they will ask for an alias/screenname (a lot of us just use what we use everywhere so you could use springcolor ifvnot taken) and a password. Then you will give them your email address, full name, street address, and phone number. If they can verify you are who you say you are with that info then you won't have to supply any other info. If they can't and/or you have a public email (yahoo, hotmail, gmail, etc) then they may require you to send them a copy of your DL or a utility bill with your name and address on it to them. I just scanned mine into the computer and emailed it to them or if you don't have a scanner you could take a photo and upload it then email it.
This is to keep scammers (buyers and sellers) from getting on the lily auction. Since I can create a gazillion fake alias online and be anyone I want to be they just like to make sure you are who you say you are and this keeps anyone not legit off the auction.
Mike will not sell or give your info to anyone else, it is just for their verification purposes.