Various options and various steps to secure to your hearts' content. From what you have said to date, I already know your login and password - so there, is one thing to change.
Go into the router settings and look for WEP and go through the motions there. Also, do you want to let people know that your network exists? There is an option for SSID broadcast. This just beams ou your network name, which is almost certainly just "Netgear" at present. Knock it off and it will stay quiet.
Any more needed, just post back. By the way, some peeps have found the setting up of encrypton and passwords to be a pain in the bum. Just read through it gently and follow the idiot guide. the DG, like mine is a great router and will give you years of happy exp....