How to use winrar and how to Open, Compress, Split and Extract rar files Video
On the video you will see how to rar a file up how to open a rar file and how to split a large file into smaller pieces and how to extract it back.
Here is the link to winrar - http://www.rarlab.com/download.htm
Winrar is a great tool to compress file's to smaller size files. you can even compress a whole folder containing multiple files at once.