You need to buy the game on Disc.
then you can consider what mod(s) you need to add to your game.
Further I don't think you're going to be a very good modder since:
In Your haste to post You must have missed the Bottom Main Menu choice for MODDING.
And obviously the Banner lettering: Modding questions belong in THE MODDING FORUMS!
Where You click on the underlined words.
Thatís where You can find Players who ARE dedicated
Modders, they are more likely to give You some assistance!
Be careful to post in the correct forum topic, as they can get persnickety about that.
The San Andreas Forum is for UN-modded game questions, and problems.