Step 1: Make a new document at 250px by 75px, fill it with any color... I chose black
Step 2: Ok now on a new layer take your Rectangular Marquee Tool and make a selection in the middle of your document. Fill it with white for now. You should have this so far.
Step 3: Now go to your blending option of your white rectangle and fill in these settings. (Stroke, Inner Glow, and Gradient Overlay) *!Only Edit the Settings I show you!*
!* Leave the gradient overlay at default but change the color *!
Step 4: Now make a new layer. And now we can add some detail to our button, take out your Rectangular Marquee Tool and make a selection from the top to half way through, fill that with white. Like below, then with that layer selected Ctrl+Click on the button layer and say select inverse then delete. After that lower the opacity to about 10%.
Step 5: Ok now just add some text and a little details and you are finished.
