Want to divide my 60 gb hard disk into 4 or 5 partition. Then how to allot space n what should be written in bytes to do equal partition.

Most partitioning software will do the math for you.

Is this the only drive in the computer? If, so, make the C: partition a little bigger. Over time, the C: drive tends to bloat up with a lot of stuff.

If this is an ADDON drive, and you already have a root partition (C:) on another drive, then partition 60 gigs into 4 15gig partitions is fine.