Pammay,
It sounds like your image is simply bigger than a bit of A4 paper so you need to either use the "Fit to page" option in the Print settings box, or scale down (or "resize") the picture so that it is smaller than the page.
I'm not particularly experienced in image editing but I know that, in the Paint software that comes with Windows, there's a Stretch/Skew option on the Image menu. In there, you could, for example, "stretch" the image to 50% of it's original horizontal and vertical size in order to make it half as big as it was originally. That's likely to fit onto the page when you print it.
Microsoft Photo Editor has a "Resize" option on the Image menu.
All other image editing programs should have a similar feature.
If you can find out the actual image size (or "attributes") of the picture, that can allow you to calculate exactly what percentage to resize it to. A standard A4 bit of paper is 210mm wide x 297mm tall. Take off 10mm from each side for the margins and that leaves you with a useable area of 190mm x 277mm. So, for example, if your image is 380mm x 554mm, you would need to resize it to 50%.
Hope that helps
