If your trying to get to Sky's Rim is what you mean, then read the tutorial Ingredient has posted.
However, if you're trying to get to Ascension Island, then you have to jump up the platforms in the Lonely Cave (where you start off) to get to the portal at the very top.
I've delt with someone (whilst playing the game) where they keep on falling of the platforms whilst getting to Ascension but it's more of a glitch, not them accidently doing it.
That might be the case.