I downloaded msstv program, but have no idea how to integrate it with the remote receivers on the internet..any suggestions..
In my experience, this will vary depending on your sound card, and more specifically, how it allows you to route the audio coming from it.
The audio built into my current machine's main board offers no provision for looping the output back around to the input, so the only way I have found to get the SSTV program to work with that one is to physically connect the line out to the line in and let it listen to itself. Doing this ties up the output, so you may need to either use a second output for your speakers, or a Y cable in order to listen to it and feed the SSTV program at the same time.
I have a second sound card though. That one (an old Creative Sound Blaster Live card) has provision for an internal loopback (called "What U Hear" in the recording selections), which feeds the output back around to the input internally. Enabling this can lead to some nasty feedback if you have a mic enabled too, but it makes it easy to feed the output of the player that's handling the stream from the Internet receiver into the slow-scan software.
Using a second sound card is a bit tricky sometimes, since you end up having to point programs at the right sound source and output (and a lot of them don't have that option - they just use whichever one you have set to be the default in the system settings), but it makes connections a LOT simpler if you want to use the computer for radio purposes and as a normal machine, too. No fiddling with wiring or connections - one sound card is just for normal use, and the other one is always hooked to the radios and ready to go.