Hi Linda,

Winrar should work as the assignment files are plain .zip files.
Which OS are you using to download these files?
If it is Windows, download Winzip software from this link : http://winzip.en.softonic.com
If you are using any other OS, search for the Winzip version for that OS.
After downloading, install it and right click --> open with --> win zip and then you should be able to see the extracted files.

Please post, if it don't help.
Happy Learning @ Dezyre !!