Cannot connect trade site to www.pathofexile.com

I fail to be able to connect my game account to the https://www.pathofexile.com/trade2/search/poe2/Standard trade site, there seems to be no explanation, there is no tutorial. When i created my account on this webpage i used a different name then my game account, is that the issue? How does it work? Can it be reset.
ELI5.

I cannot rename my account or select a character myself, i cannot select a character.

Can customer support please contact me? Thanks in advance.

Fixed it.

Solution: Go to "Home" on this page, then "My account", then "manage account", connect to steam or whatever you use to play poe2, after login steam will ask you to confirm linking your account -> confirm. Then you should be able to "whisper" other players on the trade site an trade.