There are two ways to mark a Step as complete.
The Quick Way
Step 1 – Display the Goal list.
Step 2 – Click in the arrow at the bottom of the Goal that has the Step you wish to complete
Step 3 – Click the circle to mark as complete.
The Long Way
Step 1 – Tap on the Goal the Step belongs too.
Step 2 – Select the Steps tab at the top of the screen.
Step 3 – Select the Step you wish to mark as complete.
Step 4 – Press the Completed button in the Step Status Field.
Step 5 – Reward yourself for completing a Step towards your Goal.