The first thing you ought to know is that you won't wreck your computer by trying to installing a CD drive, the worst thing that you happen is that you could kill your computer by static (so make sure you discharge any static), otherwise it should just be fine. So don't worry about it, just have faith in yourself and you'll install it in no time.
Okay, so here are some general instructions that might help you.
Firstly, you can install this CD/DVD drive along with the other ones, provided that you have space for it (you need three things to install a drive: 1) IDE cable (if you are using that) 2) The space to install it (like another bay) 3) You need power cables.
And this is what you basically do to install it (the instructions for your particular model might be different, but I'm sure this might help you)
1) Open the CPU cover
2) Remove the expansion bay cover (if you are install it on another bay), if not then remove the screws on your older drive, then remove the power cable, and then remove the IDE cable and remove the drive
3) Put your drive in place
4) Plug in the IDE cables (these are the flat ones) and then the power supply cables
5) Screw the drive into place and put the CPU cover
The only thing that you might want to pay attention to is the jumper, I recommend keeping the jumpers on cable select, so that you don't have to pick the master (the main drive) and the slave (the drive that needs a master drive).
And you're good to go! That's all you do, so you shouldn't have any problem with it!