control panel> (in windows 7) change keyboards or other input methods (in other versions) regional and language settings> keyboards and languages tab> change keyboards> add> scroll down to and selct hebrew from the list. click the little + to the left of the list item and check the “hebrew” entry. click OK.
in word, if you want to change to hebrew entry simultaneously push the left alt key and the left shift key.
you can also use the on screen keyboard (vista and 7) for help mapping where the keys are.