Re: I would like my ad to appear at the top of the page.
The problem here is that everyone who advertises would like to be top of the page...
There are a number of factors that will determine where your ad appears.
1. your bid. The higher you bid, the higher your ad is likely to appear.
2. the Quality Score of your keyword - the higher the quality score the higher your ad is likely to appear
3. what your competitors do - the more competition there is for your keyword, the more important 1 & 2 become.
Let's look at how this works.
If your keyword were "blue widgets" and no-one else was interested using this keyword - and if you had a website dedicated to blue widgets (high quality scores), then you'd pay next to nothing to be top of the ads - you might even be the only one!
But if everyone was trying to attract visitors looking for "red widgets" - and if they all had fantastic websites (high quality scores) and were prepared to bid $50 for each click (there might be a lot of profit in red widgets) - then you'd have to pay $51 to be top of the page....
This is oversimplisitc - but it gets to the core of the matter.
Work on your quality scores - that's free (more or less) and then figure out where you can pitch your bids to get an ad position that works for your business model... which may or may not be top of the page.....
hope that helps