The SQL Server transaction log operates logically as if the transaction log is a string of log records. Each log record is identified by a log sequence number (LSN). Each new log record is written to the logical end of the log with an LSN that is higher than the LSN of the record before it. Log records are stored in a serial sequence as they are created.
The contents of the latest transaction log is displayed in this view, including individual LSNs:
The log is written to when log buffer data is flushed and that is when new transactions appear. If your T-SQL uses names transactions it is easy to see if they have made it to the log file for low level log issue debugging.
The "Refresh" button loads the most recent data into the log viewer.
Read more about the logical and physical architecture of database tranaction logs in this MSDN article