From the main UFT window, click on "File - Print Setup - External Support".
In the dropdown box under Editor, select "Microsoft Word".
Click on the "Browse" radio button under to the "Path to the editor" block.
Follow the path to the "winword.exe file. This should populate the "Path ...." block.
Note: normally the path is something like "c:progra~1window~1winword.exe"
Click OK and you should be setup.
You can find where it is on your computer by clicking on "Start - Find (or) Search - for Files and Folders", enter winword in the first blank box and click Find (Search) now.
The path you get will be a long name path and has to be convrted to a short name path. This is done by using the first 6 characters of each folder name, a tilde "~" and a number. normally this number is 1 but it can be 2 or 3 depending on how many folders that you have that have the same first six characters.