Assistance from someone smarter than me

So i;ve been messing around on paint making my own little experiments of backgrounds for sigs and a few charries. I am less than a beginner but i am proud of my work nevertheless and would love to put them as my sigs every so often. But as i am technologically challenged, i really need some help figuring out how to resize them to upload them or someone to walk me through uploading them at all. Im sure i sound ridiculous but ive been googling and come up with nada.
 so SOS help me please! 

I just sent you a PM! :)