Help with Spanish homework...?

I don't really understand the directions so I'm not sure how to solve these, but could you just help me with one? The first one is.... El arbol(accent on the a) esta(accent on the a) ________ casa. Okay but I know the directions want me to find where things are around the house and it wants me to fill in the correct preposition plus article or contraction to complete the rest of the sentences. But I'm reallyyy bad at spanish lol and I don't know what a Spanish prepostion, article, or contraction would be. No idea. Lol please give me some examples or some tips. Thank youuu!! [: