When someone buys a lens from you. You will want to go to your paypal account and send them an invoice for your lens. Just log into your paypal account and click the tab that says "request" money. Type in their e-mail and the amount you want to be paid. Click goods and then type a note if you like. I always say something like thank you for the purchase of abc lens or something like that. Click Send.
Wait until you have been paid.
Then go to your Squidoo dashboard and look down the left hand side of the page where it says transfer a lens. Just simply follow the instructions.
Keep in mind the buyers Squidoo e-mail and Paypal e-mails may be different. So be sure to find out from your customer which one to use.
Have fun flipping Lenses.