The general instructions on how to submit your Thesis can be find on this page. The basic instructions for connecting a linux system are similar to the ones for Mac users, but you need to introduce a little more detail.
If you need to submit your document using Linux, follow these instructions (valid for the Gnome graphic interface):
If everything is ok you'll be asked to enter your gaspar password and you must decide if you want that the system record your password or not, this is up to you, I suggest to avoid the registration in order to maintain an high security profile.