Can you help me out?? greatly appreciated!?

hi! my sister is going to have surgery..(not too serious but she will be in the hospital for at least 5 days after) anyway i bought her a diary for when she feels bored. i am going to write her a letter in it for when she opens it she will be surprised. i want it to be kind of emotional. (she is 11, im 14) i want to tell her im trying to be nicer and do things with her and i don't want to fight with her. i want to get the point across that i really do care about her but with her stuck up attitude she is making it hard can you help me get things organized without me making me sound naggy or annoying. she always complains that im annoying and stupid and dumb and names im just tired of her i want to make amends. PLEASE HELP! :) thanks!