How to you get a thread to go to a new page?

[HoHo]

I notice some threads have multiple pages so not all posts are visible at once. Does this happen automatically? I'm asking because my Pictorial Trip Report is getting long, and if someone wants to read a new installment that have to pull the whole thing up, which could take a while if you don't have broadband given how many pictures there are. Having new posts appear on a separate page might be good.

Thanks, HoHo