Just follow the instructions below:
1 - Install winzip (www.winzip.com) and winrar (www.winrar.com).
2 - Download both zipfiles (Quake1.zip and Quake1b.zip) with the links on the previous page and extract from those two .rar files to one directory.
3 - Open the .rar file and extract the quake folder you see in winrar to your harddisk.
4 - Download and extract the executables update from the previous page and upzip the file to your quakefolder on your harddisk overwriting files.
5 - Delete all files in quake\id1\glquake and copy c:\windows\system\opengl32.dll to your harddisk \quake.
6 - Try run glqwcl, if it doesnt work try qwcl, Have fun!