I have a question about how games, and other software can be installed on the Ubuntu OS. Such as counter Strike, World of Warcraft, and Half Life

Yes, some games can starts with wine, look this: https://help.ubuntu.com/community/Games
In particular: https://help.ubuntu.com/community/Games#head-e62f867682d01fe04b27e8ff2cf175435fe18ccd where you can see that in the list there are the games that you have cited.

Bye

Windows games will always be best in Windows. Some of them can be run quite well in Linux via Cedega or Wine, for instance. Cedega is the better choice of these for games, as it specializes on getting games to work. WoW for instance is said to run very well in Cedega. But Cedega isn't free, Wine is.

Another solution could be to run Windows in a virtualized environment, side by side with Ubuntu. There are many virtualization solutions, but Vmware is one of the better choices end users. Vmware Server and Vmware Player are free of charge, while Vmware Workstation costs money.

More info about Cedega and some of the of the games you mentioned:

http://www.cedega.com/
http://games.cedega.com/gamesdb/games/view.mhtml?game_id=3518
http://games.cedega.com/gamesdb/games/view.mhtml?game_id=3356
http://games.cedega.com/gamesdb/games/view.mhtml?game_id=3337
http://games.cedega.com/gamesdb/games/view.mhtml?game_id=3189

More info about Vmware:

http://www.vmware.com/products/
http://www.vmware.com/products/ws/

I WHOLE HEARTEDLY suggest you run wow in wine, not Cedega.

Wine runs WoW flawlessly! Just get EnvyNG and install your graphics driver with that, then install the latest version of wine, edit your config.wtf file and make the following changes to your wine's registry and you are in business!

Open a terminal window, (konsole/terminal/x terminal etc..), type regedit and press enter. This will start the Wine equivalent of the windows registry editor. If you are familiar with using the registry editor under windows then this is pretty much the same.

   1. Find HKEY_CURRENT_USER\Software\Wine\
   2. Highlight the wine folder in the left hand pane by left clicking on it. The icon should change to an open folder.
   3. Click right on the wine folder and select [NEW] then [KEY].
   4. Replace the text "New Key #1" with OpenGL (CaSe Sensitive).
   5. Right click in the right hand pane and select [NEW] then [String Value].
   6. Replace "New Value #1" with "DisabledExtensions" (CaSe sensitive).
   7. Then double click anywhere on the line, a dialog box will open.
   8. In the value field type "GL_ARB_vertex_buffer_object" (without the quotes).

Add these lines to your config.wtf file in your World of Warcraft directory

SET gxApi "opengl"
SET Sound_SoundOutputSystem "1"
SET Sound_SoundBufferSize "150"

This info was taken from various guides across the internet.