What. Do. You. Mean. By. That?
The answer is A thank me later
The word "cheap" in this sentence doesn't mean "not expensive" but rather "low-quality" or maybe "easy to break".
Nikita is the only witness to see you doing it but she made it up
To prove your innocence you would have to been with other people they would serve as witness saying you didn't do it even when you know you didn't in order to prove your innocence.
I'm not sure if it answers your question
Just write something simple. For instance, your friend's name is Jack (or anything of your choice), and the item of your desire was a bike. You wanted to buy it because you were extremely inspired by a bike race you saw on TV a few weeks/months ago. You managed to get half the money from your dad, but the other half was from a part-time job you worked at as a barista/delivery driver/accountant whatever it is that you applied to solely for the sake of affording the bike.
Now that you've bought the bike, describe your excitement to learn riding it, your happiness of how you reached your goal and so forth. It should be easy.
I'm being vague here in case your assignment is an online one and there is chance of you receiving a plagiarism strike. I hope this helps.