HT4628: Wi-Fi: How to troubleshoot Wi-Fi connectivityLearn about Wi-Fi: How to troubleshoot Wi-Fi connectivity
Your wi-fi should have a password that you created. Only you will know that unless your network is unprotected. Depending on your router and who set it up, you may have a default password that came set up. Sometimes the password in printed on the modem/router. Look for it and check your user manuel for it.
It's not necessarily a problem.
In order to have secure wifi so that nobody else can access it, you have to have a WPA2 password. Whomever set up the wifi account more than likely set up a password so that it would only be accessable to those with that set password.
Your best bet is to figure out who set up the password and what it is so that you can utilize wifi.
Hope this helps.