A simpler way to import models is to open up the compontents box. Type in what you are searching for. It will show the various models from the 3D warehouse. Click on the one you like and then click on the field to drop that model in your current file. You do not have to sign in or even have an account with google.
I do not have Sketchup on the computer that I am typing this from, so can not give your more detailed instructions, but it is fairly simple.
Dan