Sounds like the idiots who sent it doesn't know how to create a proper form in Word (a common problem). The formatting probably messes up because they have repeatedly used the Space bar to create the input boxes. When you type in there it pushes all the spaces along.
You have 2 choices. You can make sure you delete all the spaces that exist after you have typed in your bit (no guarantee with this, because if you have to enter more characters than there are spaces, it'll still push the formatting out).
Alternatively (recommended!), print it out and fill it in by hand.
[A third option would be to overlay the input areas with text boxes, but this is not good practice either]
It is possible for you to make it into a proper form and lock the formatting, but it takes a bit of time - and why should you do all their work for them?
Let me know if you need more help. I actually like doing this stuff (god, how much of an anorak am I???)...