Maybe you should do some preliminary work and use google or wikipedia to find out, what's .rar (Winrar software), .zip (Winzip software), .7z (7zip software) and .001 (hjsplit software) and then try to figure out how they work.
If you're able to unpack and join archives (that's what these software programs are for), you can ask again about .wmv, .avi, .mpg and so on.
Here you can find some links to these programs:
https://www.forumophilia.com/topic107906.html
Monkey D. Ruffy