Step 1: Sign up
Before you can even think about 3D printing objects you have to sign up for Ponoko at http://www.ponoko.com/make-and-sell/pricing-and-signup. I would recommend to only use the prime service if you are going to print a large amount of objects/products using ponoko. Choose a unique name and password. After you have done this sign up for google sketch at http://sketchup.google.com/. It's really simple and fast to download.