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 a 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.