The file that your installation setup is looking for is the "Doctor Watson" launcher (dwtrig20.exe). From the error message you posted, setup is looking for the file on you installation media in the U.S. English directory "office.en-us".
What all of this means is that your installation media is probably corrupt. If this is a legal copy of Office, you should be able to get a replacement disk from MS at no cost. If you have a friend with a copy of the disk, you can borrow it to complete your installation. You would just use your own registration code.
If this is a pirated copy of Office, corrupt files are common. You're on your own in that case.