Ok i am the Admin of the forum but still i don't see any option for making any topic pinned or sticky . Can any one help me to find it plz.

I wonder if the posting options are minimized, so you can't see.
When you make a new post, beneath the 'Preview' and 'Send' buttons, there's an Options section that has a + on the title to indicate the section needs expanding; the Normal and Sticky options are in there and you set as required before posting.

What if i want to make it stick after it got posted , like any other member posted it.

Just click edit on that particular post, scroll down to posting options and click "Sticky" then click save