Let's begin with what you have? Then I'll know better what you might add. Since they only asked for 1 paragraph, you won't have to say that much . What you DO want to say is why you will be a valuable employee for them. That usually "sells" them on your resumé.
i have that i want to be a cook, and i have that i like to work in a kitchen and that i love to prepare meals. and i said im creaitve and artistic and a good cook. but i don't know what else to say because our teacher said it has to be really long
What I meant is: let's see what you have in Spanish. You must write this in Spanish, right? Look at your textbook, select the vocabulary you know and use that! You can become very inventive, but the simpliest thing to do is to always use the vocabulary and structure (verbs, etc.) that you have studied.
I'll be happy to supply vocabulary if that would help you. Here are some topics: meals, preparation of food, meat & poultry, fish, Seafood & Shellfish, Fruits, Meal & Menu Components, Dairy Products, Eggs & Related Foods, Grain s & Grain Products, Condiments, & Spices, Drinks, At the Table, Dining Out, Buying Food & Drink, Describing Food & Drink.