how I make a simple model animation?

[alexmantor]

yeah well nothing complex, just make the unit get burried in ground until dissapear in 3 secs. Like changing the flying height but with negative numbers. Right now the only program that I have is the wc3 model editor but idk if thats enough for doing that.

Pls don't just tell me the program i need to use, explain me how to do that I said.