A chart of the typical Boeing 747-400 seating arrangement can be found on Boeing's website. However, each individual airline and possibly each individual aircraft within an airline's fleet of 747-400's may be arranged slightly differently.
Check with your airline. Often, the seating chart for your exact plane or flight can be found on your airline's website.
Another great resource for finding and comparing seating charts is SeatGuru.com by tripadvisor. SeatGuru allows you to browse and compare 920 seat map for 111 airlines. Featuring a sortable chart of seat size, seat pitch and seat amenities such as wifi, power outlets and video, SeatGuru gives you access to advice, user comments, photos and comfort ratings to make your next airfare purchasing decision easier.
Alternately, you can Google Boeing 747-400 seating chart and then click on the Image tab to get a quick overview of the many possible seating configurations for the Boeing 747-400.