Simple:
* I cooked dinner last night.
* The chicken is cooked.
* The chef cooked a delicious meal.
With context:
* I cooked the vegetables until they were tender.
* The potatoes were cooked in the oven for an hour.
* She cooked a storm in the kitchen, preparing a feast for her guests.
Figurative:
* His plan was cooked up in secret. (meaning it was made secretly and probably not very good)
* The deal was cooked. (meaning it was finalized, but perhaps not honestly)
As a noun:
* The cook added a touch of spice to the cooked. (meaning the food that was already prepared)
The way you use "cooked" will depend on the context and what you want to say.