How do you allocate hits to Traffic exchange?

I started by saying "Let's use http://www.traffichills.com/ggnn as an example:" So all that I said refer specifically to only that example. So, you'll understand me better if you go to that site.

Your credit balance listed on the left side of what?
Apsense Network or Apsense Traffic?
If it is Apsense Traffic, then the answer is yes!
Simply use the Apsense Traffic Converter.

If it is Apsense Network, then the answer is no!
It can't be used for the Apsense Traffic exchange.

Nevertheless, it can be used to showcase your own sites.
All you have to do is look under the Credits Balance.
You will see a red button called "Promote on Apsense".
Click this button and a "drop down" menu will appea

Let's use http://www.traffichills.com/ggnn as an example:
1/ Register as a member
2/ Surf for credits or buy credits
3/ Go to the menu on the left and navigate to My Websites
4/ Add your website(s) as Step 1 and Assign Credits in Step 2

Thanks Justin, but can I convert from my credit balance listed on the left side to hits to be allocated in the TE? And how?

It is actually quite simple!
First you surf and gather website "hits", which shall be reflected under the Account Report (the blue box on the left hand side of the page) ==> Traffic ==> "Hits Available".

Secondly, go to the Dashboard (right hand side of page) and then click "My Websites".
On this page, you shall see a list of your websites.
Under this list, there is an "Auto Hit Allocation" box.
Click the "Allocate Now" button.
This will evenly spread hits across unpaused/approved websites.