Where Does the Adsense Code Go?

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Hi

I have 68 Classifieds v4.1.6 Developer.
I have been looking around this forum to find out where to but the absence code so that ads would appear on my website. As vbulletin has special boxes where I can just past and copy the codes, then 68 classifieds does not have them, So far I have found out that I should put the codes somewhere in layout tpl file that I can access trough my admin panel ( I might be wrong ) anyway I was trying to stick the code in some places that I thought It should go but it eater messed up the whole page or appeared on the wrong place.

So My question Is: Where do I but the absence code in order to have ads appear.

1. On the top navigation bar on the right side of the logo
2. Under the Left navigation box.

Is it the file that I mentioned above and inside what part of the code should the codes go in order to have ads appear on these places.

And do I have to but any code around the ad code.

Thank you