Hello and welcome on Gothicat World!
You can find some guides in the "Guides" tab on top of the page (I think you are directed to the first one when you start the game?), but they may lack some informations, so feel free to indeed ask if you have any question.
I hope you get your free jewels, the GW staff have no direct influence over the free options, they're displayed by random advertisers, so it sometimes doesn't work... But there shouldn't be any problem with Paypal
To put an avatar, you have to go in the "Forum"/"Profil" tab, that is where you can change informations displayed in the forum. There you can go in "Edit avatar", where you can upload a picture from your computer to be your avatar
I made you a little illustrated tutorial:
And the "Edit signature" next to the "Edit avatar" is to modify your signature
A lot of avatar here are made by other players, but I don't think there is a lot of artists on the english side offering that kind of service. But if you want, I can try finding you someone who could on the french forum, if you have some idea of how you want it to look. Or you can just put a picture that is less than 200 pixels of length and width
EDIT : Seems like Jiji was quicker than me