I want to secure my network

Can you please provide addition detail? Your request is light on details.

If "by secure" you mean you do not enter a password to access your WiFi access point, then you need to log in to the router/access point that controls your WiFi connection and configure it.

If you're wanting to increase the security/encryption of your WiFi network to more than what it is, if your encryption is anything less than WPA2, make sure you WiFi access point/router supports it and select it.

Please detail more specifics.