Make sentences using these words: through / before / behind 

I'm looking the birds through the window. --> I'm looking at the birds through the window.​  

I'm writing homework before my friend. --> I'm writing my homework before my friend.​

Theirs many paper on the wall behind me. --> There are many papers on the wall behind me. 

=> Corrected : The sentences are corrected grammatically.

​He took his son's hand. --> He grabbed his son's hand.

The president urged the citizens to unite. --> The President urged all citizens to unite. 

She is battling cancer.​ --> She is fighting cancer.

=> Another way: Your sentences are okay and these are another way of saying it.