iMovie Assistance Please

I have about 63 minutes of HD camcorder footage that I am
having downconverted to DVD quality (through camcorder output)
to iMovie.

Have already uploaded the 63 minutes as 1 file.

I need to break it down to 6 segments of 10 minute videos.

I basically start playing the first clip. I then measure out
approx. 10 minutes using the slide ruler.

How do I save that 10 minutes as a file then start putting
together the next 10 minutes and so on?

Would appreciate the assistance.

Also, any way to save these files so I can stream them on the
Internet?