here's a mini-guide.
download winrar (
http://www.rarlabs.com/rar/wrar37b8.exe)
right click your file and click "Add Archive" see pic:
check out the "Split to volumes, bytes section" see pic:
in that input box, put the size of each "chunk" you want in bytes.
I always convert megabytes to bytes using this converter:
http://www.t1shopper.com/tools/calculate/
After getting the byte value, simply put it in the box and click "OK".
Enjoy
