when i click on phone number its not going to pop-up for dialling

href attribute of link should be written in this way:
href="tel:+2313321312"

can you explain it where to write it

@abuzarkandwal
You should already know that, otherwise it does not make sense to ask how to do something, if you have no idea where.
It's probably item.php

please be professional you have no write to behave your client like that
i m not a Student of computer science i m law student so its not a big deal if i don't know about it
if you want to explain so explain it from abc other way thanks

This is support forums for anyone, not for clients, customers or whatever.
If you are student of law, you probably not going to advocate someone without acceptable level of law knowledge, just by asking someone how to properly advocate. You will probably first study law, then ask if you have some questions in particular areas, not vice versa.
It's same here, ready to help, also with coding, ... not ready to baby sit and tell you code, line number, file location etc.

ok as you wish but on other platform they explain everything
for example phpbb forum ,hivepress