First thing to do is resize it by opening it in microsoft paint (cos most people have it) If you don't know how to do it. Open pic with paint, On the tabs at top click image then strech/ skew and resize item by 50% or whichever size you prefer. (don't forget to save it)

Once you have done this go to http://www.imageshack.us/
they Host your pic (for free)

Then copy one of the forum links they give you and stick it in your post

Easy peezy lemon squeezy.