To add an allowance claim type you will need to go to the Adminstration settings, then to Expenses. From there you will need to open Categories.
Click the Add new button, from here you can create allowance claim types using the Main category details, Allowance and Alowance rates sections.
To make the allowance claim category you will need to make the category type Allowance.
To edit rates you will need to click on the Edit rates button which is found under the Allowance section.