Expenses can be added from two places: the Business page screen and from a job's detail page. Expenses added to jobs can be marked as billable, which means when you create an invoice for the job, the expense will automatically be added as a line item.
To track a general expense, go to the Business page and open the blue popover menu on the upper right. In the menu select Track and Manage Your Expenses. On this page you can see a list of all of your expenses, click into them to see their details, and create new expenses. Click the Track an Expense button to add an new expense.
On the new expense page choose the date of the expense, the category, a name/description, and the total. You can also add a picture for the expense, which is handy for keeping up with photos of receipts. When finished, click Track this expense to create it.
Adding expenses to jobs is done of the job's detail screen. First find the job you want to track an expense for from the Jobs page. On the detail page, open the blue popover menu on the upper right and select Add an Expense. Creating a job expense has all of the same options as a general expense in addition to the option to make it billable or not. Billable expenses will automatically be added to a job's invoice. Job expenses can be viewed from the job details as well as the Expenses page.