Quake 2 was the natural progression from editing for Quake 1. As you can see, I did not make quite so many levels for Quake 2 as Quake 1, mostly due to the extreme length of time it took to rebuild a map. Even still, those maps which I did complete I am quite proud of, especially the "Ruins of Ascenzia" which is generally well-liked everywhere.
To install either of my Quake 2 levels, unzip the zip file directly into your Quake 2 directory, making sure to unzip the paths as well. The files should go into their correct location, and you can simply run the map by using "map ruins" or map"wtplant2" from the console. If you want, you can also edit the maps.lst file and add an entry for the map. The file is pretty self-explanatory, you should be able to figure it out.
If you want to make your own Quake 2 maps, you should probably look into GtkRadiant, which is the successor to QERadiant that I used. I found it very efficient once you get used to it. There are also some tutorials there to get you started.