I assume you mean the section for "Choose your Garmin Device".
I don't think it really matters what you pick here. All it does is give you instructions to install the Communicator plugin or the ANT Agent software.
The first step should have created a Garmin account, so you can just login to Garmin Connect with that, then click on upload to get activities from the device. I think the 60CSx and 78s will work for uploading using the Communicator plugin.