When configuring each of your Steps, you must associate it with one of five difficulty levels. This is to show learners how difficult the Step will be, as well as determine how high potential rewards can go if it's set as a graded Step.
Why not further brand your instance by naming those Step difficulty levels the way you wish?
To change your Step difficulty levels, while in the admin panel head to your "Config" section via the "Settings" menu.
On page two of the Config Wizard, find the section "Difficulty Level Names". Each Level will show its default description within its text box; simply select the text box and write what you wish to replace it!
Be sure to "Save" when done!