Hello dbdbgriggs,
The USB port and Linux port are physically different, please take a look at the following pictures.
They have marked the Linux ports in both the Gen1 and the Gen2, you will be able to enter Linux through these ports as I explained in my previous post.
If you want to learn how to use the Arduino IDE and start uploading sketches, why don you take a look at the Galileo Getting Started - Mac?
Peter.