On Microsoft Word I think all you have to do is hit file password and you can put in a passowrd. You might have to save it first though. I got the instructions for Word Perfect 10 right out of the Help thing:
1 Click File Save as.
2 Choose the drive and folder where the file is stored.
3 Choose the file format from the File type list box.
4 Type the filename in the Filename list box.
5 Enable the Password protect check box.
6 Click Save.
7 Type a password in the Type password for document box.
8 Retype the password in the Retype password to confirm box.
9 In the Protection options area, enable one of the following options:
· Enhanced password protectionprovides greater document security and case-sensitive passwords, but documents saved with this option enabled can't be read by earlier versions of WordPerfect
· Original password protectionprovides case-insensitive password protection used by WPWin 6.0 and WPDOS 6.0a