how to create a partition

how to create partitions on hard disk (like PC's)? Because, If I put my all data in Home folder, If I re-install the OS, my data will lost ???

You can use Disk Utility to create partitions and these are fairly comprehensive instructions for moving user folders.

However, a couple of things to consider:
1. It's very rare that OSX need a clean install
2. Your solution won't protect you from disk failure

Personally, I'd go for a physical, external backup disk using Time Machine and/or an online backup solution such as DropBox to protect your data from harm.

Its better to having backups rather than partitioning thanks a lot