Allowing the user to ask for an item if required

[madmin]

 I want to place a seperate section in my site that allows the users not only post their available listings but also ask for a new item if required.
The asked items should be placed in a seperate section and provided a link in the main navigation bar.
I need some help in achieving this.

The site should contain a publish your add button and also a ASK HERE FOR AN ITEM button to ask for any required thing.
Hope anyone ca understand this question.
Any kind of help is highly important and thankful. You can PM me for any extra details.
Thanks.. !!