Im sorry that I don't have many details to share but I am looking for a movie from when I was a kid and I saw this movie about a kid who opened up a book and the book sucked him in? Maybe, not sure, but as he went in the book it was a red and white hypnotic kind of thing and he became a cartoon character. He met some other cartoon people and there was something about this green monster or something. I remember it but I can't remember the title of the movie. Can someone please help? Sorry for the lack of information.

The Pagemaster.
Amazon.com: The Pagemaster: Macaulay Culkin, Christopher Lloyd, Canan J. Howell, Alexis Kirschner, Jessica Kirschner, Guy Mansker, Brandon S. McKay, Stephen Sheehan, Ed Begley Jr., Mel Harris, Patrick Stewart, Whoopi Goldberg, Joe Johnston, Pixote Hu

No, I remember that movie, it had a boy open a book, he wasn't in a library he was in his house and it happens right after the opening credits, he made some friends but not meeting 3 books he learns to love later. It's a boy with dark brown hair and the opening or closing credits are like shots of downtown New York or something like that. NO I remember it wasn't a book it was a box he looked into. Yes I forgot. I'm sorry.

The Phantom Tollbooth (1970)

This seems to fit my description but are you sure there isn't another movie like that too? The animation in the one I remember is different than the movie you have shown. Or another version of that movie? I know it's a kid who walks around in the beginning and opens a box, but its smaller I think, and its just a white box with a bow on top, opens it up and it's a portal I think he gets sucked in. sorry for the lack of information its been a good 10 or 12 years since I scene it.

Just for the heck of it, have you tried the original movie The Neverending Story ?
It has a dark hair boy, a book, a fantasy world, and a New York type setting near the end. Also try Neverending story III as well.

Amazon.com: The NeverEnding Story: Noah Hathaway, Barret Oliver, Tami Stronach, Gerald McRaney, Drum Garrett, Darryl Cooksey, Nicholas Gilbert, Thomas Hill, Deep Roy, Tilo Prückner, Moses Gunn, Alan Oppenheimer, Wolfgang Petersen, Wolfgang Petersen,

Hm, yeah I know the never ending story, I guess it had to be the phantom tollbooth, well thanks for yall's help!

The Phantom Tollbooth had the boy driving a car and visiting different people and was sort of an educational story. It had different school subjects at each stop like math, english, science, the weather,.
Is that basically what the movie was about?

Hm, I really can't remember what the movie was about, I didn't know if it was educational or not, I really thought it was a story about a boy that gets sucked into some other world and just explores it, I know it starts very similar to the phantom tollbooth but I guess the movie I'm describing isn't any other movie. I remember this kid was just curious to know, he opens a box and then all of a sudden he sees a cartoon world and gets sucked in. he meets strange creatures and I know one was some green thing. I know the animation style was that of the dr suess original grench cartoon movie.

Parts of it do sound like the Phantom Tollboth

In P T
Boy is laying on sofa talking on a phone.
A box is delivered he opens it. It is a phonebooth. He gets sucked in.

He is then in a cartoon driving a red car.
Meets a policeman, an old lady, a weather man with a hot air balloon that keeps talking about weather and whether.

The green thing sounds like the cave where they sing Don't get stuck in the Duldrums.