Sorry for not replying before to your question. I hope this answer will make up for it
To install an avatar you can click on the 'quick links' link on topright of each page. A popup menu will appear where you can select 'edit avatar' (see attached image). Then you have three options:
1) choose one of our pre-installed avatars
2) link to an avatar/picture somewhere else on internet (url)
3) upload an avatar/picture that is on your computer
@1 We have installed many avatars already. You can see the available, pre-installed avatars here: http://www.tcb-world.com/misc.php?do=showavatars
@2 you can also use custom avatars. If you want to use a nice picture that you've seen online, just rightclick on that picture on a website and choose 'properties'. In the new popupmenu you see a link (see picture 2). Select that link (url) and rightclick on it and select 'copy'. Then go to the page on tcb-world where you can edit your profile and paste that url into the box where by default stands 'http://www.'. The new link will appear. Press 'save changes'
@3 Click on 'browse' and select a good picture that is on your harddisk. After selected the picture, press 'save changes'