Can someone tell me how exactly buying and selling options in Tiger brokers work?

Start with these two videos:

Options basics: https://www.youtube.com/watch?v=SD7sw0bf1ms&t=1...

Options Greeks: https://www.youtube.com/watch?v=SD7sw0bf1ms&ab_...

Then once you understand these, you can read up on strategies. This website is pretty good (not mine):

https://www.projectoption.com/

Once you understand that, paper trade for a while in a demo account to understand assignment and see if you can stay profitable over a period of time.

Then once you're confident, you can move to a real money account.