How to continuously focus while videoing on Nikon D5000?

Hi! I ordered the Nikon D5000 last week and it arrived today and I'm wanting to know how to do a few things. I'm HOPELESS at reading the Manual and stuff because its all too confusing for me because I have no clue about cameras since I'm just starting out. So I would like to know how to get my camera to always focus while I'm taking videos?

E.g. If I'm filming people, I want it to focus on them but if I were still videoing, and I wanted to film something with writing on i, t how would I get my camera to focus to be able to read the writing too?
Sorry if it doesn't make sense. Basically, I just want it to focus everything.

Any help will be much appreciated!

Added (1). How can I manually focus while recording then to do the same thing? Which button do I use? (YET AGAIN, I don't really know what to say since I'm new to cameras)

Autofocus the default should sort that out for you but "focus pulling" is an extremely sought after skill in the film/movie industry as it is of course essential, most home movies suffer from variable focus and shake

The D5000, unlike the newer D3100, does not have any sort of autofocus when recording video. You have to focus manually.

The only two cameras by nikon that can do that are the D3100 which effectively replaced the D5000, and the brand new D7000

I hate to say it but a video capability on a DSLR is still a novelty, and none of them do it as well as a proper dedicated video camera. A camcorder will do the autofocussing you require and give you much better sound and longer durations as well. With your current camera you will need to keep focussing by hand, which is only practical if you put the camera on a tripod. To use manual focus, you have to look on the lens for a slider marked A/M and slide it to the M position. You then focus by turning the ring on the front of the lens.