Several times, I have gotten a message which says:
"Safari cannot download/open this site because too many pages are open".
If it's the same as the iPhone, if you look in bottom right corner of the Safari screen there is the 'Page' icon. If should have a number in it. You can open a maximum of 8 pages. So, if it says '8' then you need to close some of them.
Probably the easiest way to add WiFi networks is to go the the iTunes App store and download a free app called WiFinder. It will find WiFi systems in range and allow you to join the open ones with one click.