Problem with inserting adsense code in theme’s integrated banner

WordPress theme that I use for my blog has some integrated banners like 300×250 etc for placing ads. Inserting ads into these banners is very simple, just put the image link and the ad link; banner ad shows up live.

But you know google adsense codes are contextual and can’t be inserted into those banners that way. I want help from you guys to guide me on how to insert google adsense into those integrated banners. I hv seen ppl using same theme as mine hv placed google ads in those banners, so I know its possible.

I am not good with PHP coding so if I need to change some template codes to make it work pls make your answers brief and present it as tutorial so that I don’t mess up my live blog.