Newbie question: Image/logo header
 

Have been searching the forum for own banner questions and they all seem to be complications as to after the banner is loaded up, or html codes which I know nothing of and cant understand.

Does anyone kindly know where I go to :
1.upload my image logo from my desktop to vbulletin ?
2.What size this image should be to fit in to the header?
3.How I make the image I've uploaded in to the header
4.Can I make the banner a link to my site from the forum?

Many thanks for any help anyone can give me.:)