Q: what exercise to make my shoulders wider

A: You cannot do anything to increase the shoulder width at the bone level, but you can develop your shoulders to some extent to create the impression of wider shoulders. It comes down to two things: good upper body development -- shoulders obviously, but also wide upper back and thick traps -- and narrow waistline. Slim waist will give the impression of wide shoulders.

For the shoulder and upper back development prioritize shoulder presses, upright rows, side raises, shrugs, pullups/pulldowns, and rows (all of these can be found on my Exercises page). For narrow waistline you may need to lose extra body fat -- read my Lose Fat article for the comprehensive approach to fat loss.