Hello! 8)
How to make sigs: Go to the 'User CP' section. Then go to the Edit Signature section. That's where u can create your sig!
How to make thingies in your sig: Go to the fan art request section and request what you want for your sig! Or do it yourself if you are good at it!

Then, check time and time again to see if the person has finshed with it and then when it is. Right click on it, click properties and then copy the url/address. Go back to the Edit Signature section and then copy the url onto you sig using the image tags on. they look like this:
Oh and welcome to SPP forums! ^_<
oh and if you want to lern to sprite and make things go here>
www.freewebs.com/howtosprite/