How to add a dell dimension 5000 xp home edition as a wireless connection

Find your router under the available wireless networks in your area. Connect to it and when asked for the password enter the wireless network password.

most of the dell win xp laptop come with a dell wlan wireless card utility that can be accessed from start > all programs list where you could scan and connect to your wireless connection with hopes that you know your network name and security key or passphrase as it might be referred...
else you could connect using the windows wireless zero configuration (WZC) to scan and connect to your network ,you will find lots of useful tutorials on the net for both ...hopefully that should help you...