> I want to include it to this directory.
The only thing you can do is suggest the website to the best category. Please read the FAQ for more explanation.
> How long do I have to wait.
This is an irrelevant question as DMOZ is not a listing service. After you suggested a website an editor will review it. When that will happen is something nobody knows.
> Is there any proper process to approve link?
Yes.
1) you suggest a website (preferably after reading the guidelines and checking if it is a listable website)
2) an editor will review the website and list it when the website is listable
Nothing more.