My three machines all run Windows 7 and I won't be rushing to do anything when Microsoft's so-called 'support' runs out in January. Indeed, I've not bothered updating any of them for several months now anyway. Stop panicking!
Connecting a Windows 10 laptop to a wifi network should be dead simple though. Start here and, if necessary, tell us where it goes wrong for you:
https://support.microsoft.com/en-us/help/4027030/windows-10-connect-to-a-wi-fi-network
NB: Make sure that you use the CORRECT password. It's NOT the password for access to your computer or for logging into your Microsoft account (if you've got one) or for your email, etc. It will be on a label attached to your router and/or on the paperwork your ISP sent with the router.