Hi @Bee01,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Step 1 is to remove any of the remaining paper that is raised. You can usually do this by hand, but a paint scraper, which will be used later in the process, can also help. You need to remove any paper that is raised. You will be repairing it after, so don't stress if it peels back further than you anticipate, which is likely. If there are any hard edges where the torn paper ends, you can give them a light sand with a sanding sponge.
Once the surface is solid with no flaking paint or paper, apply a thin coat of Zinsser B-I-N Primer Sealer Stain Blocker Aerosol to the ripped plasterboard. This is a shellac-based primer, which is good for use over ripped plasterboard as it is not water-based and will not cause the paper to swell. The purpose of this primer coat is to help the plaster compound, which you will apply after, stick, as well as blocking the moisture from the plaster compound from causing the paper to swell, which will cause bubbling.
Once dry, use your metal paint scraper to apply a thin skim coat of Less Mess Multi-Purpose Joint Compound to the damaged area. Apply it about 100mm wider than the damaged area and feather out the edges to ease the transition to the existing plasterboard. By going wider, you will ease the transition between the existing wall and your repair. If you try to go too narrow with your repair, it is difficult, borderline impossible, to really hide the transition. Trust me, wider is better when it comes to plaster repairs.
Once dry, sand it smooth with your sanding sponge, wipe away the dust, apply a thin coat of your primer, then paint with a suitable interior paint, ensuring you allow adequate drying time between coats.
Let me know what you think, and if you have further questions, please don't hesitate to ask.
Jacob
