The downloads should have been .iso files, not .rar files.
You have to burn iso files to CD as images. If you uncompress them, then burn them to disk it won't work, and you can't just copy the .iso file to the disk. Again, they have to be burned to disk as images.
You'll find lots of hits regarding how to do this if you do a google search with these keywords: howto burn iso to cd
Good luck with your new Linux install...