Here is a basic walk through of taking a model from download to print, using a design I made on Tinkercad. I download it, clean it with Netfabb, orient it in Replicator G, slice with Skeinforge and print in Pronterface.
There is a missing step however. After modifying the reprap.xml in Replicator G, you have to go back and select Solidoodle 2 from the list of Other Printers. You might also have to quit and restart Replicator G to get the resized platform to show up. My install of RepG seemed to remember that I had used a Solidoodle profile before and brought it up automatically.
This is a lot of different programs to use, and everything can be simplified using other software like Repetier Host which will orient, slice and print all by itself. There are some issues that need to be addressed when using that one with the Solidoodle, and I will cover it later.