To see the step by step solution, go to 'Options' and select more steps, for example 'a lot of steps' and click 'Apply'

Then you will be able to see more steps, and by clicking on each, see the explanation.

Please note that you cannot click on the very first expression, which is the original problem. Quite often, several transformations will be performed within the same step. Use the explanation navigation buttons to step through all of them: