diff --git a/README.md b/README.md
index 29d730b..1c42150 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,14 @@ String api_base_url = "http://192.168.1.100:5000";
 
 Add the files to your Arduino IDE, install all necessary libraries, configure the board and USB/serial port, compile the sketch and then upload it.
 
+## Usage
+
+Execute the server (see below) and power up the ESP board. The following user interaction is possible:
+
+* short press of the upper button: executes a shell script / system command / program (Server config parameter 'shell_cmd')
+* long press of the upper button: sends a serial commannd to the HR50. The default command will initiate the tuning cycle during the next transmission (Server config parameter 'serial_cmd')
+* the lower button reboots the device
+
 ## Error handling
 
 * If wifi is unavailable or misconfigured, the device will show "No Wifi!" on the screen
@@ -72,13 +80,20 @@ You need a computer connected to the Hardrock-50 via USB, e.g. a Raspberry Pi. T
 
 # Configuration
 
-Open the file _hr50_rd_server.py_ and adapt the following lines to your environment:
+Open the file _hr50_rd_server.py_ and adapt the following lines to your environment regarding the USB connection to the HR50:
 
 ```
 serial_port = '/dev/ttyUSB0'
 baud = 19200
 ```
 
+Edit the following lines if you want to customize the actions performed when pressing the upper button:
+
+```
+shell_cmd = "./scripts/toggle_antenna.sh"
+serial_cmd = "hrtu1"
+```
+
 # Execution
 
 Executing this script will spawn a web server running on port 5000. This is not meant for production use and/or public exposure. Anyone able to access this server via the network can alter any settings on your HR50.