How Do I Upload Custom content ie. Paintings?

some guides

http://help.ea.com/en/article/how-to-upload-clothing-to-the-sims-3-exchange/

http://help.ea.com/en/article/how-do-i-upload-a-lot-onto-the-exchange-in-the-sims-3/

http://help.ea.com/en/article/how-do-i-upload-a-sim-to-the-sims-3-exchange/

the principle of uploading is the same for once an object/clothing is saved then use the share button then go to the launcher-exports tab-tick in the item-upload...add a description in the window that pops up  and it ought to upload to your my studio

TIP:   the exchange has a habit of culling items so don't use the exchange as a place to "save" your items to download later on if needed any item that is shared is saved in the exports folder so just copy that folder to a safe place portable hard drive/thumb drive

 and add any new items/sims/etc to the backup of your exports