Birth plan! Help!

Destiny • 1 baby boy 1-18-17
How do I write a birth plan?? I'm 33 weeks and had no idea what the heck a birth plan was until I looked it up But I don't know how to write it and when I go to the hospital who do I give it to?? Do you have to write one or is it just nice to have?? Do I need to talk to my Dr about my birth plan?? Please help me...