The manual for the Samsung Galaxy 4 phone is found on Samsung.com. You can access it from the Owners and Support section of the website.
On the Samsung.com home page, click on Owners and Support and then select Manuals and Downloads from the drop-down menu. Type "Galaxy S4" in the search box on the Download Center page, click Search and select your model from the results list. Alternatively, you can search by entering the model number of your device. When you choose your device from the results list, that model's manual download page loads. Click the Download button to download the manual in PDF format.