I am not sure where you downloaded the software from, but you should go back to that link. It will contain installation instructions.
For instance, I found a similar font at
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?locale=en_US&locBasepartNum=lj611en&prodName=Dark+Courier+True+Type+Font which states:
Dark Courier Font
Download, install, and use the "Dark Courier" font when the "Courier or Courier New" font is not dark enough.
Note: For use in Windows Operating Systems only. Do not use for DOS-based applications.
Instructions for installing the Dark Courier TT font in Windows 95, 98, ME, NT 4.0 and 2000.
* Unzip the downloaded file (make note of drive and folder files were unzipped to).
* From the Windows desktop, left mouse click on Start, Settings, and then Control Panel.
* In the Control Panel Window, double mouse click on the Fonts folder (this will open Windows Fonts folder).
* Left mouse click on File and then Install New font (the Add Fonts window will appear).
* Under Folders and Drives, select the drive and folder where the downloaded file was unzipped. The font file names should appear under List of Fonts.
* Make certain there is a checkmark next to Copy fonts to Fonts folder.
* Left mouse click on the Select All button (this will highlight all of the Dark Courier fonts).
* Left mouse click on the OK button (this will install the fonts to your Windows Fonts folder).
* Close the Fonts window and then the Control panel.
* Restart Windows. Dark Courier should be listed in your Window applications font list.
"Downtime is a Crime."