Take your t shirt and trace lines on it where you wont to put stripes of fabric... you can chose any kind of fabric but i used lace like fabric that needs no additional work on it except cutting :) I have attached my stripes by hand but u can do it by a machine if you like...

Cut the fabric in to a shape like on the pic... your sleeves are depending on the size of this piece ... attach the strait lined part to the t shirt...

And that is that :)