What are the different meditation types & how to do them?

I know there are many types of meditation, but can someone help clarify the following questions on meditation: - What types of meditation is essential for the practice & why? - How do those types of meditation work (like what am I suppose to be doing)? - Why do we do meditation (why is it such an essential thing)? If you also have any extra information to add, it would be well appreciated! (And if possible, please cite sources in the Pali Tipitaka for your answer) Metta to all!