OK so you can make mash, open a tin and steam veg so start there.
YOu need the right equipment, at a minimum a good cook's knife and a chopping board.
Mashed potato is used as a topping for cottage / shepherd's pie and fish pie.
The easiest way to make cottage pie is to buy tinned mince and onions. Open the tin, pour it to an ovenproof dish and top with mash. Add a few dots of butter. these will give you those crispy bits, bake in a hot oven (200 - 240 degrees) for 20 mins.
You can also use mash as a basis for 'pancakes' not traditional crispy ones, something more like a fishcake.
For fish buy some salmon trimmings and mix in to the mash. You can add chopped spring onion or chives, salt and pepper to taste. Use your hands to form patties and either fry them until golden or stick in the onion. Serve with a dollop of mayo or creme fraiche.
Instead of salmon you can use grated cheese, dried or fresh herbs, crispy bacon, peas (frozen), sweetcorn (frozen or tinned). Have a look what you have in.