Removing case Presario 5400us

Am trying to upgrade to DSL Received modem from AT&T, but didn't have Ethernet, so bought a Dynex 10/100 mb network card--but I can't figure out how to open my computer to install it!

I have a Compaq Presario 5400us from 2002. The photos on the Compaq/HP web site don't look anything like my tower. They show screws in the back to remove the side panel. The only screws I found loosen the fan and nothing else. There is a little wheel that looks like it's suppose to unlock something, but it doesn't seem to do anything either.

Do I have to remove the front panel to get at the side to remove that panel??

Thanks.
Frustrated in Computer Hell!

 

Most cases open from the left side if you are looking at the front, and you may have to pull kinda hard to get it out, but once you get it, it will probably seem kinda obvious

Also A link to the pics of the back would be helpful.

A couple more things.

It slides towards the back.
on the back the side panel should have a ridge coming around the corner, this is what you need to grasp and pull.(you could gently pry it with a screwdriver)
If it does not have one put your hand flat on the side and try to slide it getting as much friction as possible.
Some cases are just horrid and take a while to get open.