Note that you can link Pobble to your MIS (SIMS, Arbor, Scholarpack, etc.) to automate this process.
You can manually add pupils to Pobble via the Pupils menu. Click on "Add pupils". On this screen you can input your pupil's data one by one, or import all pupils at the same time with a .csv file (here is a guide on how to generate one via SIMS).
When you click "Save" the pupils will be created and you will return to your list of pupils.