What is your room like?
A great starting point is to learn about the different furniture and items in your room. You will also need some prepositions which will help you to talk about the position of things in your room.
You could try these exercises to practise what you've studied.
If you want to describe the items in your room then you might need to know more about adjectives.
Finally here are some fun activities and games, including sound files, which should really help to fix the phrases in your mind.