We have a DLink DI614 router and need to know how to password protect the wireless network

Connect a computer to the router with an ether-net cable. this will keep the connection from reseting while you change the settings.
open a web browser on that computer and in the address bar type 192.168.0.1
then press enter.

this will take you to the routers configuration page

click on wireless
then click on home

enable WEP

if this is for home use choose 128 bit encryption.

under key type chose HEX

under key one create a key of your choosing. it must be 26 characters long and can only have the these characters in it. 0123456789ABCDEF

once you have created a key, click apply then click continue to save your changes.

You should download and read manual pages covering Using the Configuration Menu that begins on page 10. Securing your wireless is detailed starting on page 12 for WEP, page 13 for WPA (only if you have a Radius Server - most likely not) and page 14 for WPA-PSK.

Nearly all devices support the older WEP encryption method. The downside is that it is easily defeated with software in under 10 minutes. A much better, more robust method is WPA-PSK. It can not be defeated (yet). If you choose WPA-PSK, any device that you connect wirelessly to this router MUST support WPA-PSK as well, otherwise it will NOT be able to connect.

I hope this helps and good luck. Please rate my reply, thanks.