Hey everyone! Trying to invest here but don’t know how that works.

I know how index funds are not volatile like individual stock and I want to put my savings in one of them.

I heard a lot of the S&P 500 but I don’t really understand how can u out my money there, whereas with VTI I can see the trade button in WeBull app

So basically what I’m saying here is, how do I invest in the S&P 500 and would be a good investment if I buy VTI stock ?