TD Ameritrade Roth IRA

Can somebody please explain this to me. I’m a college student and I use an individual account with TD Ameritrade worth around 10k. I’ve began doing research and just started learning about Roth IRA’s.

Can I open one in TD Ameritrade does anyone know and how do the “Rules” per say work? It’s to my understanding that u can withdraw tax free at 59 1/2, is that true? What if a person does not wanna wait until that age, is it worth opening a Roth? Lastly, how does it really even work? Do I get to pick the stocks that make up the Roth or is it some automatic fund like spy?

Thanks all in advance, just need a little help