diff --git a/README.md b/README.md
index 9fa2d39..80042ce 100644
--- a/README.md
+++ b/README.md
@@ -3,20 +3,17 @@
 [![Version status](https://img.shields.io/pypi/v/opnsense-prom-exporter.svg)](https://pypi.python.org/pypi/opnsense-prom-exporter/)
 [![PyPi Package](https://img.shields.io/pypi/dm/opnsense-prom-exporter?label=pypi%20downloads)](https://pypi.org/project/opnsense-prom-exporter)
 
-
-
 # OPNSense Prometheus exporter
 
 I've configures OPNSense with High Availability settings using 2 servers.
 
-* https://docs.opnsense.org/manual/hacarp.html
-* https://docs.opnsense.org/manual/how-tos/carp.html
+- https://docs.opnsense.org/manual/hacarp.html
+- https://docs.opnsense.org/manual/how-tos/carp.html
 
-So I've 2 servers: *MAIN* and *BACKUP*, in normal situation *MAIN* server
-is expected to be `active` and the *BACKUP* server to be in `hot_standby` state.
+So I've 2 servers: _MAIN_ and _BACKUP_, in normal situation _MAIN_ server
+is expected to be `active` and the _BACKUP_ server to be in `hot_standby` state.
 
-
-The initial needs was to be able to make sure that *BACKUP* server is ready (hot standby)
+The initial needs was to be able to make sure that _BACKUP_ server is ready (hot standby)
 to get the main server role with the `active` state at any time.
 
 > Unfortunately I've not found a proper configuration to call OPNSense HTTP API over
@@ -25,16 +22,72 @@ to get the main server role with the `active` state at any time.
 
 ## Metrics
 
-This exporter gives following metrics:
+This exporter gives following metrics, all metrics received following labels:
 
-* ``:
+- `instance`: by default this is set with the hostname where is running this exporter service
+- `host`: the host of the OPNSense
 
+### Enums
+
+- `opnsense_main_ha_state`: OPNSense HA state of the MAIN server
+- `opnsense_backup_ha_state`: OPNSense HA state of the BACKUP server
+
+### Gauges
+
+- `opnsense_active_server_bytes_received`: Active OPNSense server bytes received on WAN interface
+- `opnsense_active_server_bytes_transmitted`: Active OPNSense server bytes transmitted on WAN interface
 
 ## Usage
 
-
-> *Note*: Most updated documentation from command line !
+> _Note_: Most updated documentation from command line !
 
 ```
 opnsense-exporter --help
+usage: opnsense-exporter [-h] [--check-frequency-seconds FREQUENCY]
+                         [--main-host MAIN] [--backup-host BACKUP]
+                         [--opnsense-user USER]
+                         [--opnsense-password PASSWORD]
+                         [--prometheus-instance PROM_INSTANCE]
+
+OPNSense prometheus exporter
+
+optional arguments:
+  -h, --help            show this help message and exit
+  --check-frequency-seconds FREQUENCY, -c FREQUENCY
+                        How often (in seconds) this server requests
+                        OPNSense servers (default: 2)
+  --main-host MAIN, -m MAIN
+                        MAIN OPNsense server that should be in `active`
+                        state in normal configuration.
+  --backup-host BACKUP, -b BACKUP
+                        BACKUP OPNsense server that should be
+                        `hot_standby` state in normal configuration.
+  --opnsense-user USER, -u USER
+                        OPNsense user. Expect to be the same on MAIN and
+                        BACKUP servers
+  --opnsense-password PASSWORD, -p PASSWORD
+                        OPNsense password. Expect to be the same on MAIN
+                        and BACKUP servers
+  --prometheus-instance PROM_INSTANCE
+                        Exporter Instance name, default value computed
+                        with hostname where the server is running. Use to
 ```
+
+You can setup env through `.env` file or environment variables with defined as default values
+(so command line will get the precedent):
+
+- **CHECK_FREQUENCY_SECONDS**: default value for `--check-frequency-seconds` param
+- **OPNSENSE_MAIN_HOST**: default value for `--main-host` param
+- **OPNSENSE_BACKUP_HOST**: default value for `--backup-host` param
+- **OPNSENSE_USERNAME**: default value for `--opnsense-user` param
+- **OPNSENSE_PASSWORD**: default value for `--opnsense-password` param
+
+## Roadmap
+
+- allow to change the listening port (today it force using `8000`)
+
+## Changelog
+
+### Version 0.1.0
+
+Initial version