Go to the main menu and you will see the Settings option.Select it.

After selecting the Settings option Select Expenses here, you will find two options to set groups and categories for expenses.

Go to the second option.

After selecting the second option, You will see a list of categories already added on the screen

If no categories are created yet you can create a new category from here.

Click on Add Expense Category button.

A popup with a Textfield and a Save button will appear.

Create a category and click Save button.

Newly created expense category will be seen on the list.