How to make Feature image visible

Hello,

I am working on this site. http://wowdesigns.in/projects/nesties
I have used this theme http://wp.color-theme.com/streak/ apparently(theme author) says, the theme is build in such way that when we add "Feature Image" via Wordpress Admin panel. It won't appear on the front end.

I want to enable it, could you please help me do this?
I want to achieve in all my following pages.
1. About Us
2. Forum
3. Petition.

Please let me know how can I do this.
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I did add image here http://imgur.com/a/vb1n8
But it is not visible.

Thanks