First start off with saying how happy you are about you being her friend and how exiting it is for her to be participating in the competition and give her good luck and hope the best for her so it would be something like this; “Hola amiga estoy muy emocionada para ti. Que tienes la suerte de estar en esta competencia. Yo se que tu puedes ganar y te doy mucha suerte. Estoy muy feliz de ser to amiga ojalá ganes.”