Click on the "Nutrition" tab.
Then choose the "Food" sub-tab.
Hover over the food or food group to modify and click on the "i" which appears on the right.
Select the language (FR-FR / FR / EN / SP) and click on "edit".
You can then add an image, enter what is equivalent to a portion, put tags and modify the nutrients.
Further information
To learn how to create a custom food, click here.
To learn how to create a recipe, click here.