Hello cindyis and welcome!
Good luck with your first fast. You will find lots and lots of really good information and tips on the board about how to do this way of eating/life.
A lot of us seem to fast from dinner time one day to dinner time the next. So after dinner, only no cal/low cal fluids until bed time and sleep through until morning. Fluids only until the 500 cal meal at dinner time and then fluids only until breakfast next morning. Water, fruit tea, green tea, ordinary tea, no cal squash etc etc is fine. The important thing is to drink LOTS. It helps with fat metabolism. I would suggest being a wee bit cautious about too much caffeine as it could upset your sleep.
There is also different views about diet drinks. I think there is a thread in the nerdy section.
If you do use sugar and milk in your drinks remember to allow for the calories in them.
All said and done, this WOE is trial and error for the individual and you play with it until you find something that works for you.
Tha's what I really like about it, and what seems to be making it suit so many people and making it sustainable (although it is still early days)
Best of luck , remember to put your data into the tracker and let us know how you get on