be more agressive

LATELY I HONESTLY THINK I HAVE LET PEOPLE WALK ALL OVER ME.I HAVE BEEN TO NICE TO PEOPLE IN SCHOOL,SO THEY MISTAKE MY KINDNESS FOR WEAKNESS.ALSO THE FACT THAT IM TOTALLY SHY,I HATE THAT AND IF IWANT TO BE AN ACTRESS I GOT TO GET A BOOST OF CONFIDENCE.SO BASICALLY THIS GIRL AT MY SCHOOL NAME…..KITTY [NOT HER REAL NAME OF COARSE]BORROWED MY PERFUME AND ITS BEEN ALMOST A WEEK TILE SHE GAVE IT BACK AND I ASKED NICELY AS POSSIBLE FOR HER TO GIVE IT BACK,YET SHE PRETENDS SHE LEFT IT AT HOM. SO SOMEONE TELL ME WHAT TO DO.