Need help with edges

I want to know how to make the edge that this site has on it's main page connecting the banner to the nav bar.

http://www.maraudersmagic.com/index.php?page=home&t=News%20and%20Updates

er...
The black block, it's edge with the rounded corner?

Easy and fast way:
Make a rectangle with the marquee, then smooth the selection.

Better way:
Make a rectangle with the marquee, then pick the penTool and make a perfectly curved corner selection, and delete.

O.ö

You need to cut a rectancgle(the black space on that site)

Then, where you want the corner, draw a big enough squares in blue(the outsuide shape)

Once its done, try the select tool witht the round shape and delete the small square you just did..

I wish I was not on my laptop, i could draw an example.. But you should get it by now..