Hi, newby myself, altho I have progressed from "new" to "junior"!
Your signature is what appears at the bottom of the page when you post. If you want one click on edit signature, write what you want, then save it. You can change the size/colour of the font by clicking on the boxes at the top. If you then want to change it click on edit again. Have a look at other profiles to get an idea of what is what.
The picture above your name when you post is an avatar - it has to be very small to be accepted. I googled avatar and there are a lot of sites that let you have them for free. Only use these sites if you know you have a good security system on your computer, I suspect that they harbour nasties. You follow the instructions to save it onto your computer then add it as your avatar. Sorry cant remember exactly what to do.
The photo on your profile can be taken from any photos you have on your computer, but again they have to be small, I only had a couple that would do. The easiest way of doing both is to post your photos to a site like flickr or photobucket, I have not done this yet. There is a thread on here that tells you how to do this. There is also info on the index page for new posters you might find useful.
It will eventually become clearer, I promise! Just keep having a try at stuff. Or keep asking your daughter I have tried asking my son but he gets so impatient that I have given up.
Val