Bit of a marathon, but here goes...
First, connect your laptop to the router with an Ethernet cable. Changing the security settings will prevent Wifi connection...

You will enter something like 192.168.0.1 in your browser to access the setup pages for the routher. You have already done this I assume.
The next step is password protected, but something really easy to Google. . Like user =
admin and password =
admin. Let me suggest a password:
adm1nacc3ss. Find the relevant page in your configuration and change them to both something unique and secure. Aim for being able to change the IP address (192.168.0.1) to something else at some point in the future too. Keep the 192.168 bit on the front though.
Next, go to the page for SSID. It says 'wireless'. This is not a security setting, but it's cool if you set it to StuartsWLAN or something. It is still visible to all, uless you turn brodcasting off. I would leave it on for the moment.
Change the security to WPA (WPA2 if it's an option). Enter a password. Let me suggest one:
W1rele55acce55. Disconnect the Ethernet cable and try to reconnect by wireless. If you left SSID broadcast on, you will see your wireless network in the list. Click (double click?) on it. Mirror the settings and WPA(2) password from the router. This password is the
W1rele55acce55 one. Should be bingo!
Take care here though.
The first password you changed (admin/admin) was to directly access the router setup.
adm1nacc3ssThe second was the password to access your wireless network.
W1rele55acce55.
If you get stuck, plug the Ethernet cable back in and start from the top. Expect to make mistakes - we have all done it. (Well, I did anyway).
The passwords were suggestions of course.