Gauntlet Con starts tomorrow! Dr. Tom the Frog has put together an informative video for you (see above). It explains how to use the RSVP site and the procedure for getting into your game.
The tl;dr version: you will check in at the mustering_point channel on the Discord server a few minutes before your game. From there, your game runner will send you all the links you need to get in.
Most games will be run over Hangouts on Air and use the Roll For Your Party dice app. Both tools simply require you have an internet connection, a mic, and a browser window. It's VERY EASY. If a game runner chooses to use a tool outside of those three (such as Roll20), they are responsible for teaching you the things you need to know.
Here is the Discord link one more time:
Ivan C
2017-10-20 04:29:34 +0000 UTCIvan C
2017-10-20 04:22:13 +0000 UTC