Vista - Problem scanning

I have not very techie. I scanned several documents and attached them to an
email. The email would not go through; when I opened it up the scanned
document image was very large....just one corner of it filled the screen.
What am I doing wrong... what is the difference between a jpeg, tiff, etc.
Like I said..... I really don't know much about this. Thank you for your
help.

The problem is the resolution, or "quality" settings of the scanned image. This is shown in actual height and width in pixels. You can either try rescanning using lower settings, or resize the existing image using built in Windows imaging software or a simple viewer/editor like irfanview
IrfanView - Official Homepage - one of the most popular viewers worldwide
Or, if it a text only document, and you wish to have it appear in the same order as you scan them in, check to see if your scanner software has the function to automatically adjust for black and white documents. If so, you can avoid having them come out like typical "pictures" A jpeg is a compressed image format, a tiff is uncompressed.