Gradient?s parameters:

Create Professional Software Box in Photoshop CS

Take the instrument from here and represent a stripe.
Then select the next instrument to erase from the stripe?s end by one vertex.
Take the instrument shown here after that and blur out a little the vertexes
for the stripe to get thicker in the middle.

Create Professional Software Box in Photoshop CS

Create Professional Software Box in Photoshop CS

Blending Options-Gradient Overlay

Create Professional Software Box in Photoshop CS

Gradient?s parameters:

Create Professional Software Box in Photoshop CS