Upload & Sell: Off
not sure what you mean upload....
Maybe you are talking about proofing site?
or a place to complete transactions for prints?
there is some form of web presence ... your store front if you will (blog/web-site). Then there is a proofing site/off-site backup.
there are many options ... need to consider expenses, what you want to do....
Me: Prophoto blog, Smugmug for proofing/off-site back up.
There are plenty of options out there.