I just recently signed up for GOG, but i totally misunderstood when the site asked me for a username as i thought i would use it to log in, so this is definitely not the username i actually wanted, so im curious how i can contact someone that can change my username since im still very new to this and have no clue what im doing.

I believe this is the thread you're looking for:

https://www.gog.com/forum/general/it_is_possible_a_username_change

Answer: Contact support via a support ticket.

Hope this helps

No, this is the one he is looking for.
https://www.gog.com/forum/general_archive/can_i_change_my_user_name


EDIT: And link for support:
https://support.gog.com/hc/en-us

You sure? Maybe it was this thread:

https://www.gog.com/forum/general/can_i_change_the_username_attach_to_my_account

or how about this one?

https://www.gog.com/forum/general/hi_i_would_like_to_know_how_i_can_change_the_username_and_if_is_posible_do_it/