1) Notice the Site ID, since this will guide you later to the correct logs file for your site, in case multiple sites are hosted under the same IIS instance.
2) Open "Logging" from the "Featues View".
3) Notice the target logs location when the logs are stored, and make any required changes to the log content.
4) Sample log file should look like:
5) Lookup the status code against the below MSDN list of HHTP status codes:
Snapshots from IIS version 7.5.7600 under Windows 7 Professional.