In addition to my own freeware stereogram software,
there are several programs out there for you to try
Online Stereogram Generators
If you just want to go online and create some stereograms, or play some online games
that are based on stereograms, then you can go to one of these web sites.
There are limits to the size, colors, and images you have available - but the images can otherwise
be excellent for viewing or simply demonstrating the stereogram concept.