Oh of course I could tell you! Alright, do you know where it says "hello yourusername"?, below that there is a list of things. From those things, click "profile". After that, click "forum profile information". Okay, now you should of already decided what picture you want to add to your profile so in order for it to appear in front of everyone, go to: tinypic.com
Here, you should upload your picture and while it is uploading, go back to your profile forum information and above you could see that you can either upload a picture by choosing a file or adding a link (for now, let's choose a file .png/.jpg). This will be your mini avatar, that will show a small picture under your username, like mine.
By now, your picture should of been uploaded by now and when you go back to the tinypic website you'll see 4 urls. Copy the one that has this in the beginning '

' in the end. Once you have done that, go to your profile and paste that url in the signature box, the last one.
Finally, if you want to post a picture under a reply, click 'preview' and you'll get expressions, font colors, etc. Just do the same process as we have done for tinypic and you'll get the image below the reply.

I hope I helped!