Creating a new job is easy. Simply tap + on while the Jobs tab.

Once you've created a new job, you can tap the Job Name field to enter a name for the job or tap the Notes field to enter notes. Tapping Client lets you assign a the job to a client (if you haven't created the client you need, you'll need to do that first from the Clients tab).

Tapping either Flagfall or Rate per hour will bring up the number pad, so you can enter a value easily.

Flagfall is a one-off fee that's applied to each job. It's sometimes called a "call-out" fee. Rate per hour is the hourly rate that will be attributed to the job. If you charge by non-hourly increments, then this can be achieved by working out how much it would be as an hourly rate, then setting the correct rounding options in under the Settings tab.
For example, if you charge $1 per minute, then you could set the hourly rate to $60 and the rounding to 1 min. If you charge $10 per 30 mins, then set the hourly rate to $20 and the rounding to 30 mins.
Tapping Done will return you to the job details page.
The number pad also has some other features: tapping Default will enter the default rate you've set on the Settings tab.

Tapping Recent will open the recent menu. This contains the 5 most recent values you've used. If you haven't entered any values, then the menu won't be available.
Jobs can be delted three ways:
1. By pressing Edit while on the jobs list, then tapping the red circle, then delete.
2. By swiping across the job name in the jobs list, then tapping delete.
3. By tapping the trash can icon on the top right of the job details screen.