ok......................on the left hand side, the tool bar at the bottom has 2 boxes for your colors. the right hand side one, the one nearest you is the stroke/bleed. press on that and on the top tool bar you will be able to adjust the width.
if you click onto the boxes with colors in, one of them is the stroke box. when you click on the stroke box, the stroke tool comes up on the top of the screen, there you can adjust the width.