Need help installing vehicles and what not.

[iARMY STRONG 0]

Okay, so I just recently downloaded GTA IV off steam, now I want to install vehicle mods like cop vehicles and what not, how do I Start off?

[strike 1,581]

Download Spark IV and follow the tutorial

[iARMY STRONG 0]

and hey, strike, it keeps saying my product key isn't valid, when I clearly didn't type anything in the space provided, there were numbers and what not already in it. Do I even need my windows Live thing?

SparkIV has stopped working, when I Try to open it.

[strike 1,581]

Well, you have to type the key in the space provided Is it a legal copy?

[iARMY STRONG 0]

Yes, bought from Steam. And where do I get the key from? lol

[AlconH 1,711]

It should have been emailed to you and also been shown once you bought it.

[iARMY STRONG 0]

and do I need xbox live for the social club thing?