diff --git a/README.md b/README.md
index 0ec62fc..e541a59 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,37 @@
 # install_esp_idf
 GitHub action to install esp-idf and cache its dependencies
+
+## Prerequisite
+Your firmware repo must have the esp-idf as submodule at the repository root. If it is somewhere else, specify with `idfpath`.
+
+## Example workflow
+
+```yaml
+name: Build firmware
+
+on: push
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Fast Submodule Checkout esp-idf
+      uses: 0xFEEDC0DE64/fast_submodule_checkout@main
+      with:
+        submodule: esp-idf
+
+    - name: Install esp-idf
+      uses: 0xFEEDC0DE64/install_esp_idf@main
+      #with:
+      #  idfpath: esp-idf
+
+    - name: Build firmware
+      run: |
+        . esp-idf/export.sh
+        idf.py build
+```
+
+