How can I decorate on a mug or plate with paper?
You can use mod podge (decoupage glue) to decoupage your paper designs onto the mugs and plates - there are many tutorials for decoupage all over the he internet.
Once your decoupaged mugs / plates are completely dry and cured (leave it for a few days to be sure) you can apply several thin coats of a water based polyurethane varnish (leaving plenty of time for each layer to dry) to seal it and make it food and dishwasher safe.