GTA San Andreas was published about 7 years ago,now so there are some new GTA version like GTA IV or another but if you still love GTA San Andreas,you can also play it in different way like installing mod to your GTA to make your GTA more fun to play
The modification for GTA can be so easily found,and there are so many program which can install the mod on your PC.All thing you must do is search for the mod you would like to install using a search engine like google
Then you can install that mod with many programs like SAMI(San Andreas Mod Installer) or GTA ultimate editor.

For example you can download the mod on this site:

1.www.gtagarage.com
2.www.gtainside.com
3.www.strategyinformer.com
4.www.thegtaplace.com
and the other web

Then search SAMI with google and install it
When you already have SAMI,you can install your mod using this program


This is the example: