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 'Results'.
You can then click 'Update Measurements' from the left-hand side
You will have 3 different measurement options to pick from under the category 'Update Measurements' those being Weight & Circumference, Body Fat Measurements and Vital States.
For each, you will be able to add new measurements and see all previous data as seen below.
Just remember to hot the 'Save' button once you've entered new data.