Hi @GinnyMee,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
You'll want to start by tidying things up a bit and removing any loose material. Use either a chisel or a flat tool like a paint scraper to help remove any splintering timber.
Once splintering timber has been removed, give it a quick sand with some 80-grit sandpaper to tidy things up and help prepare the surface. Brush it down after this to remove any sawdust.
Now everything is prepared, use Builders Bog to fill the patch left by the hinges. You can apply it with a plastic scraper or similar tool. Try to get the surface as close as possible to the surrounding area, then allow it to dry and tidy up and smooth the surface with some sandpaper before painting.
Let me know if you have any further questions.
Jacob
