ok join one of those sites I listed, they are both free. Upload your pictures there, snapfish is very easy to use and re-sizes your pictures automatically.
Once your picture is uploaded right click it and choose properties, then copy the addresse of the pic. It should start with
http:// and so on.
Now come back to RC and under post reply there is a button that says img click that and paste your adresse in there. That is all there is to.
Hosting just means that they have a copy of your pic and are letting you use there web site to show us. If you have any other questions just pm me.