From your 'My Hub' page (please see below)
On the left hand side of your account, you will see the side menu in which you can select 'Exercises'.
This will show all exercises available to you to add to a workout by simply searching them individually under the 'Search Bar'
Select all of the tick boxes next to the preferred exercises that you would like to add
And click 'Add To Stack' at the bottom of your screen
And If happy with your selection simply hit the 'Create Workout' button below.
You can then add a workout name and 'Create'.