Update error message, screenshots and instructions for IDE 2.

Author: seaxwi

content/Software Support/Compilation/Compilation-error-Error-2-UNKNOWN-platform-not-installed.md

@@ -0,0 +1,17 @@
+---
+title: "Compilation error: Platform not found: platform not installed"
+id: 360020846379
+---
+
+When compiling or uploading, the following error may appear in the output panel.
+
+```
+Compilation error: Platform <platform name> not found: platform not installed
+```
+
+This error appears when the selected board is not installed.
+
+Follow these steps:
+
+1. Check that you've selected the correct board. See [Select board and port in Arduino IDE](https://support.arduino.cc/hc/en-us/articles/4406856349970-Select-board-and-port-in-Arduino-IDE).
+2. If the required board is not installed, install it. See [Add boards to Arduino IDE](https://support.arduino.cc/hc/en-us/articles/360016119519-Add-boards-to-Arduino-IDE).