You can add expenses in 3 ways:

1. Add Expense From Numbers:

Open Expenses report

Choose the last item - Add Expense

NOTE: if you want to access all categories, Check the box "Show all categories"

2. Add Expenses from the Trip Management:

Check more details here - Add a Trip Expense

3. Add Expenses From Load Management:

In the Loads menu over the load and click the View button; 

   3. Click on the Expenses

   4. Choose Add Expenses.

Bonus: You can attach a picture of the receipt together with an expense record to get rid of your expenses paperwork.