Photo Sizing

Hi All

I wasn't sure where exactly I should have posted this, but this seemed like a good place to start. I am having problems uploading pics. When I do upload a new pic, it always gets reduced to a thumbnail even though the pic is the correct size specified by the forum. I know it is preferred that thumbnails are not used so can somebody please shed some light on how I can upload a pic without it turning into a thumbnail?

Thanks for your help