The pictures next to the names are called avatars & the pictures at the bottom are called siggy pics.
To get a pic next to your name you will need to go to the 'user cp' section, just click it at the top of the page, once on that page find the 'edit avatar' link & click it, it will take you to the avatar area., find the custom avatar section & either upload a picture from your computer by clicking on the 'browse' button or if you are using a picture from the web you will need to know the web address & then enter that in the appropriate section.
avatars can only be up to 64x64 in size.
Hope ive answered your questions & havent confused you further!
If you still have questions feel free to ask, its what we are here for!