1) Open your RetrofitMe app, and hit the menu button in the top left corner.
2) Select the "My Data" option on the menu.
3) Press the '+' button in the top right corner.
4) Ensure 'weight' is selected, choose the date you want to enter weight for, and then type your weight into the text box.
5) When you are done, hit the save button in the top right corner.