Hello, admin of the Custom Variants club here:
We don't usually monitor this forum, so future questions are better asked within the club; that aside, if you paste a testing game into the text box at the start screen, the variant submission screen will pop up. There's a very helpful pinned thread that links to a video so you can visually see the process, if I didn't explain it well enough 
I made a chess variant called Minichess which is like normal chess but 6x6 (middle is shortened from 4 to 2 rows, pawns can never walk 2 squares and instead of 2 Knights and 2 Bishops the players get 2 Archbishops). I think the variant is good enough to be public on the Variant Server so I joined the Custom Variant Club and read how to upload variants. My big problem now is that if I click on the variants.world screen I just get to the main discussion screen and not to the Variant submission one. Can anyone help me with this?