your english is fine
please make sure you have read lisa's tips...make sure you close parts of the cage and make the environment as comfortable as possible for your parakeet.
from what i have read, it takes time for them to adjust...so please be patient and see how things are...there is a possibility your parakeet is afraid of the new surroundings
its hard to tell on the condition of your keet as we cant see it and i am not a vet...but usually the signs you can see from
1. ruffled feathers all the time
2. not active at all...not even moving at all
3. keeps closing his/her eyes (not only one eye)
4. look at he droppings (poo) is it runny? is it normal?
i'm still new but, i just recently bought one too and it turns out to be sick and i had to give her back...
if your in any doubt whats best is to call the petshop where you bought your parakeet and ask questions also you can call vets, or even better give it a checkup through a vet...
hope this helps...and anyone who is more knowledgable please correct me if there is any mistake in my explanations
take care and hope your parakeet will get better soon...