Splitting your WINRAR files to parts

1. Open the WinRar application and choose the source file,

2. now right-click the file or folder you want to split, 

3. and select "Add files to Archive" or simply press [Alt] + A. which opens "Archive name and parameters" window, 

4. now find among tabs (on the General tab) "Split to volumes, bytes" select the option which suites you best. 

5. Afterward press Ok.

NOTE:

But let me inform you that the split on both the 700MB media disc will only serve as data backup, and won't be able to work without any of one dics. Since both the splits (assuming to 2 splits only) need each other to get extracted and work as a single data.

Good Luck!