Upload & Sell: Off
There are many software programs, there are many template companies, there are online templates through some of the print houses for cards and magazine covers, and there are programs that allow you to create the things yourself. It all basically falls upon what your skill level and/or time allows you to do. Some people are very talented at creating templates, some people can pick it up very quick, others buy pre made templates and put the images in, others upload the photos to labs and let the labs take care of everything.
Up to you....Google can be a good friend...