Which server do I choose?

[Iscah]

Also OOT but how do I upload an avatar here or yet select an avatar on the forums?

Avatars are automatically uploaded from your in-game character and current(ish) equipment. I think it gets updated daily sometime during the night? Maybe at daily reset time or a bit later.

Anyway, keep it in mind when you log out that what you're wearing will be your avatar for the next day or so.

If you have more than one character, you can select which one is displayed in the forum settings.