diff --git a/CHANGELOG.md b/CHANGELOG.md
index fbcc3b6..991756a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## [Unreleased]
 
 - ✨ — Allow to customize agent User-Agent header (#78)
+- 📝 — Document how to add data to requests (#77)
 
 ## 0.7.4
 
diff --git a/docs/checks.md b/docs/checks.md
index 8e961e2..82ee77e 100644
--- a/docs/checks.md
+++ b/docs/checks.md
@@ -82,6 +82,48 @@ caption: argos-config.yaml
         - json-is: '{"foo": "bar", "baz": 42}'
 ```
 
+## Add data to requests
+
+If you want to specify query parameters, just put them in the path:
+
+```{code-block} yaml
+websites:
+  - domain: "https://contact.example.org"
+    paths:
+      - path: "/index.php?action=show_messages"
+        method: "GET"
+```
+
+If you want, for example, to test a form and send some data to it:
+
+```{code-block} yaml
+websites:
+  - domain: "https://contact.example.org"
+    paths:
+      - path: "/"
+        method: "POST"
+        request_data:
+          # These are the data sent to the server: title and msg
+          data:
+            title: "Hello my friend"
+            msg: "How are you today?"
+          # To send data as JSON (optional, default is false):
+          is_json: true
+```
+
+If you need to send some headers in the request:
+
+```{code-block} yaml
+websites:
+  - domain: "https://contact.example.org"
+    paths:
+      - path: "/api/mail"
+        method: "PUT"
+        request_data:
+          headers:
+            Authorization: "Bearer foo-bar-baz"
+```
+
 ## SSL certificate expiration
 
  Checks that the SSL certificate will not expire soon. You need to define the thresholds in the configuration, and set the `on-check` option to enable the check.
diff --git a/docs/cli.md b/docs/cli.md
index a9aac5e..e524a8c 100644
--- a/docs/cli.md
+++ b/docs/cli.md
@@ -61,6 +61,8 @@ Options:
   --wait-time INTEGER             Waiting time between two polls on the server
                                   (seconds)
   --log-level [DEBUG|INFO|WARNING|ERROR|CRITICAL]
+  --user-agent TEXT               A custom string to append to the User-Agent
+                                  header
   --help                          Show this message and exit.
 ```