It depends which operation system you are on.
If you don't know which system you are running go to "my computer" or computer in the start menu and click it. Then right click the C: drive and go to properties. Somewhere on this page it will tell you whether you are running windows xp, vista, 7 etc. It will also tell you if you are running a 64 bit version.
The next step will be going to the website for this card printer
here. Look for your operating system and install the program for that version. (Download to your computer, find the file, double click it, and press run or continue if your computer warns you about it.)
It might help if the card printer was not connected to the computer when you run this program, but connect it later.
If you cannot run the program, it may be you don't have the "privileges" to run it, in that case you will want to ask your IT department (if applicable.)