1/ Join this website, its free!
http://photobucket.com/
2/ Click on the 'Upload' form and it will give you options of where you want to upload your picture from ie. my pictures, desktop, my documents, etc.
3/ The picture needs to be a jpeg or gif image (not bitmap). You can convert this in programmes like Windows Paint.
4/ Choose your picture and upload it, at this point check below the form what dimensions you are uploading it at. (this website max is 640 pixels i believe).
5/ When the picture is uploaded, move your cursor over it and it will give you link options, you want the link. Copy and paste it onto here.