Writing a script to backup up /home/username
 

I need to write a scritp that can list all users dir and backup them up individually as .tar

Can some one please help

Automating backups with Tar
As for getting a list of all usernames, you're best bet is probably going to be to 'cat' /etc/passwd and pipe it to 'cut -d : -f1' inside a loop.

for retrieving user names

just awk would do

tar cvf home.tar /home