Simple: You click on "Post AD" and start posting. make sure you give a good description of what you are posting and maybe even a picture.
If you plan on posting more than 1 ad and using TheProffer.com often, sign up for an account, it is simple and free, but it allowes you to manage all your ads from one screen, and best of all, no email verification!

Simple, ANYTHING, you can post anything but be sure to only post 1 time in any catagory for that city.
You do not like looking for something only to find the same item listed many, many times!
This can be flaged and removed by other users.

You can post ANYEHERE that your product or service is offered. if you are in the US and you have a auto for sale, Your ad in India would be flagged and removed. However if you had an internet based business, or were say, an immigration lawyer, then this would be fine.
You may post is any and all cities you wish your ad to be viewed.

Flagging is a method that you the user can help keep the site clean and clear of SPAM and unwanted advertising.
when enough people flag an ad, this ad is removed and the admin can review it. we may decide to repost, delete or move the ad to the correct city/catagory.