First you must make a gatherling account at www.gatherling.com (please use your mtgo name as your gatherling name for pairing purposes)
Next you must find the event in your "player cp" tab and register. It will then ask you to upload a deck. An easy way to do this is go to your collection on mtgo, right click the deck name you want to use, export it as a text file. Then open notepad and open the file. Copy and paste into gatherling.
10 min before the start of the event, open a new chat on mtgo by clicking the chat dropdown in the top right corner and select join new. Then in the bar type #frontier and hit enter.
Please try to be 10 min early to the event chat room so we can deal with any questions you may have.