The Log Viewer is located in the left menu of the Web Configuration.
In the Log viewer, you are able to look at the log files for every application that supports log files.
Each drop down contains a list of available log files for that category, be it an application or the system itself.
If the list is empty, that just means that system has not generated any log files.
Log Rotation
Every log file is configured to be rotated every 10 minutes at a size of 1 Megabyte. Once a log is rotated it will appear in the same list table as the other log files, and can be downloaded at any time.
To view log files that have been rotated, you will need to extract the log file from the compressed archive. You can use many tools, one of them being the free software 7zip.