Hi Jenny,
You can also suggest to google what keywords or paragraphs within your text that you would like them to target by using this code:
<!--google_ad_section_start -->
your keyword or text goes here!
<!-- google_ad_section_end -->
Once you implement the code it takes a couple of weeks for the ads to adjust.
If you put your ads within your text it will get more clicks but remember to put them "above the fold" because they pay better.
To find high paying keywords, I like to use the
adwords keyword tool. To use it, just put in the keyword, get the results. Then, where it says "Choose columns to display::, choose "Show estimated Average CPC". Next, where it says, "Calculate estimates using a different maximum CPC bid:" put in the amount $100 and hit recalculate. Then click on the column header titiled "Estimated Average CPC". Next click on the little black up arrow next to Estimated Avg. CPC. This will you give you a general idea as to what advertisers are paying for ads for those words. Of course this will not tell you what you will make per click but it will give you ideas as to specific keywords to choose.
Hope that helps,
Kathy