How do I create an ad??

[brandtorrent.com]

You've gotten some good advice here but to answer your original question: You can use software like Adobe Illustrator or Photoshop if you have it to design an ad. There is also a free program called GIMP (do a search for it) that let's you create images. That said, having the software to mess around with is different than having the design skills to create a nice ad. One thing to check out is http://www.adready.com It has ad templates and will help you generate an ad. You could also hire a graphic designer if you have the budget.

If you're looking for general marketing tips that are free or inexpensive you may find my blog helpful -- http://www.brandtorrent.com/blog I blog about inexpensive/free marketing and working with a cross-promotion partner.