Updated readme

Author: cmaglie

README.adoc

@@ -1,8 +1,22 @@
-= Wifi firmware/certificates updater the Arduino Wifi 101 Shield =
+= Firmware/Certificates updater for the Arduino Wifi 101 Shield =
 
 Use this tool to update the SSL root-certificates installed on the
 WiFi 101 shield.
 
+== Usage ==
+
+1. Upload the sketch "FirmwareUploader" in your board. You need to
+   install the lastes WiFi101 library (available through the librayr
+   manager of the Arduino IDE).
+   The sketch should be available as an example of the library too.
+2. Run "winc1500-uploader-gui".
+3. The tools is able to fetch root certificates directly from the
+   websites, just write the IP or domain in the text box and click
+   on the "Fetch" button.
+4. Select the serial port of the board running the "FirmwareUploader"
+   sketch.
+5. Click "Update" button.
+
 == How to build ==
 
 go get go.bug.st/serial