Android:
Wireless. Enable it. If there's more than one signal, choose the one you have access to. Enter the password if there is one.
Laptop:
Depends on the laptop, but usually once you select the signal (and enter a password if needed) they connect.
Be aware: "Wifi is now available" doesn't mean "there's a signal showing". It means that you have the legal right to use that signal. Piggybacking off a neighbor's wifi signal is theft of service, and is usually a felony. (And is vigorously prosecuted by the internet company.) If your internet company is providing "free wifi", you, as a customer of theirs, have the legal right to use that signal.