Hi Elaine - dont worry I had all these troubles when I first joined too!
Now your avatar can be done by going into 'User CP' right at the top of the screen on the left hand side. You then get a little list come up with differnt opions to edit. Under settings and options is 'Edit Avatar' click on that. You then need to tick the box 'custom avatar'. 2 options will appear. 1 is to upload a file from your pc, the other is to link from a hosting website like photobucket, if you have it, if not use the first option for now. Click on browse, this lets you search your documents and pictures on your computer, add the image you would like and then 'save changes'. Hope this makes sense.
As for signatures we have a signature shop where lovely hi tech ppl on the forum make them for those of us that are less able!! Here is the link
http://www.hamstercentral.com/commun...ture-shop.html
Just post some photos that you would like and say what colours, font, patterns etc you would like and they will do it for you