I was surprised to discover just how easy it was. With today's technology it couldn't be easier. Armed with a radio, computer and a set of images one can get a SSTV station going for a very modest amount.
Lets make some assumptions.
As a radio ham you'll have a radio. You will also have a computer. You'll also need an modem. A modem 'modulates' data into tones and 'demodulates' tones into data. With modern PC's you don't need a modem.