How to print separate images from one large one?

I have a history project, and long story short, I'm cutting out a map of Guinea on a sheet of posterboard. Thinking I would be smart, I found a picture of Guinea on Google Images, cropped it, flipped it, and resized it to one page. Then I cut my posterboard out to be proportionate to the 8 1/2 by 11 sheet of paper. The proportion is 3.29 to 1. (Posterboard to paper). I've resized the picture on my computer using this proportion, by multiplying the pixels of a full sheet of paper by 3.29. Now all I'd like to do is print this large image onto a few sheets of paper, (probably 6-10), and then tape these to my posterboard, overlapping. Then I can put a few dots on the borders, take them off, and presto! I have the outline to my country dotted on my posterboard. Then I could cut it out and wa-lah! But my computer printer doesnt have this option. What can I do? How can I turn an oversized image into many smaller ones, and print those out?