Go to the CP Exchange (accessed by clicking the # of CPs under your portrait, then "Exchange CPs" at the top of the page that loads.
If you have not yet submitted the image to the Art Team for approval so you can use it, scroll down to the second set of textboxes on the page, and beside "What do you want to do" select "New." Then enter the information and upload the images for the entity. Then you need to wait for approval, which may take a day or two depending on when the Art Team is doing approvals. Once it is approved you will get an event notification letting you know. Each new image submission costs 250 CPs.
Then return to that same page and go back to the same textboxes, except this time next to "What do you want to do" select "Personal" (assuming you set access to private rather than public--if the latter, select "Public"). Then you can just click through the screens to choose the images that were approved. Each application costs 100 CPs.