Hi and welcome to Muppet Central. Let me try to clarify the matter.
So far, Disney has released The Muppet Show: Season 1 and Season 2 as individual DVD boxsets. The Season 1 collection has all twenty-four episodes from that first season of the show, the Season 2 release has all twenty-four episodes from then as well. There are two different packaging variations of each: the normal cardboard box version, and a felt cover packaging variation; the Season 1 has Kermit's signature collar, the Season 2 has a mock-up of Misss Piggy's head.
There were 45 episodes released in a total of 15 volumes, three episodes each, labeled as The Best of The Muppet Show by Time-Life. These contain a sprinkling of episodes from all five seasons, but are far from complete.
You could also contact some of the tape traders here on the board to get the remaining three seasons or wait until these are released by Disney in turn. Hope this helps and have fun exploring the rest of the forums.