If you are still learning, you should, as Tom pointed out, let us know
what you've got so far.
You should also let us know which version of Powershell Windows you are
using (some commands will not work in every version of either).
If you haven't done so, make yourself familiar with the following commands:
- get-childitem
- move-item
- remove-item (including parameter "-force")
- sort-object
- select-object (parameters "first" / "last")
Then read:
http://blogs.technet.com/b/heyscriptingguy/archive/2015/03/09/use-powershell-to-create-zip-archive-of-folder.aspx
If you then still have questions regarding your script, post it here and
aks specific questions.