A short introduction for remoting printing to a third-party printer.
Step 1: Choose a third-party printer preset and press the config button for connections. Fill the hostname or ip:port and the API key/Password for the printer.
You can test the connectivity to the printer by clicking the "Test" button.
You can find the API key in octoprint user settings as shown in the following picture.
Step 2: Slice and press the "Print" button. "Upload" means only uploading the gcode to printer and "Print" means uploading and printing the gcode file.