For your first question, you could give them a link to
/wp-register.php on your site. Then they could register their own name.
As for the latter questions, there is a way to embed banner ads in WordPress. How you do so depends on the advertisers. You often need to insert a piece of code into the appropriate place in your template. In some cases, you need only add an image with a static URL (e.g. to a post). It may point to various sites and may also change its appearance.
Lastly, *yes*, you are allowed to use WordPress to make a buck. With most advertisers this can be hard though, so don’t raise your hopes.
> Also is there a way to place banner ads on WordPress?
There are some plugins which can help you insert/manage advertising in wordpress.
You can use my Adrotator plugin to insert any kind of advertisements in your WordPress template.
> Is it allowed to be used for commercial use?
Yes. You can check my blog for ideas.
