Once you get into the Selenium test runner and clicked onto the run all tests button or run the individual test button, you will see the content in the middle and bottom frame change (refer to the picture below to identify the frames correctly).

In the middle frame (2) you can see the commands that the test is running, while the bottom frame will show the ongoing action with full rendering of the page being tested (3), and the left frame (1) will show the tests that have been completed and their status.

The table that shows the commands is a table that is split in three parts, which replicate the selenium test command/target/value setup (command is the command being run, target is the optional element on which the command is performed, and value is the parameter of the command).

When the command is being processed, it is highlighted in yellow. After a command is executed, it is highlighted in a color that depends on the command outcome.

Commands that have been executed successfully but that were not perfoming any check are highlighted in light green (in the example above, the type command), while commands that have performed a successful check are highlighted in dark green (such as the verifyTextPresent command above).

Commands that have failed, or have performed an unsuccessful check, are shown in red (and we have no example of this, because KSS just works™ :P).

The same color coding holds for the left frame where the executed and yet to be executed tests are shown, with the notable exception that there is no distinction between light and dark green (it wouldn't make much sense anyway).