After the completion of my workbench I noticed it got cluttered really fast. This is how I built a shelf to help with organization.
Be careful with any power tools you use and take proper safety precautions.

Step 1: Stuff You Will Need

Ok heres what you will need to make the shelf. These are the main things I used but you may want a slightly different shelf so this will vary. I spent 10 bucks for my entire shelf.
Materials
1-6in by 1 inch by 6 ft board
4-L Brakets and screws they come with
8-2.5 inch decking screws

Tools
Stud Finder
Power Drill
2 Small Plastic Buckets
Screw Driver
Level

Step 2: Find Studs

Just what it sounds like, use your stud finder to locate the studs. I like to draw brackets over where they are.

Step 3: Attach the Brackets

Hold your board up to the wall and mark where the studs are onto your board. Now screw your L brackst onto the board where these marks are. Use your screws that came with the brackets.

Step 4: Set Up for Installation

Set your plastic buckets up in between the stud marks and set you shelf on the buckets. Make sure your brackets are lined up with the studs. Make sure this is level.

Step 5: Attach to the Wall.

Now all thats left to do is attach the shelf to your wall. You can pre drill the holes but I didn't and it worked fine. Screw your 2.5 inch screw through the holes on your brackets and your done.