If you know the name of the chapter you want to visit, just type it into the Chapter Name box, and press the "Find" button.
Most likely you'll want to search by City or by Meeting Day. Just click the drop-down menu and select the City or Meeting Day that works best for you, and you'll get a whole list of chapters to check out.
Before deciding on a chapter to visit, be sure to check the chapter's membership roster to make sure that your profession is not in conflict with someone already in that chapter. Remember, a BNI chapter can have only 1 person from any given profession.
This is a good thing... we all depend on this feature.