There are plugins that you can download through wordpress.org. It'll create an area within your dashboard and you can create a customize them and place them in columns or within posts. It's called Adsense Manager
. I've used it on a site that I've done and it's pretty easy to use.
There is a drawback, not with the plugin, but with Wordpress itself. You're only allowed 3 adsense ads on at a time, but you can "cheat" in a way and for text ads, have them long either height wise or width wise and they'll put multiple ones on there.
If you have any more questions, feel free to ask.
"I would feel more optimistic about a bright future for man if he spent less time proving
that he can outwit Nature and more time tasting her sweetness and respecting her seniority."
E. B. White (1899 - 1985)