I learned this off a YouTube video

Step 1: What You'll Need:

1.) You'll need stone

2.) Redstone

3.) A lever

4.) a note block

5.) and a redstone torch

Step 2: Build It

Place a stone block down

2.) put a redstone torch behind that

3.) put a block on top of the torch

Build it across, I didn't make mine to long

Do the same thing as you started

After you do that, leave a space and put another stone block. Leave another space and place another one.

After placing the second block, put four blocks on front (shown in pic)

Place your lever in front of the four blocks where you left your second block

Start your redstone a few blocks ahead of your first stone block

Connect your redstone up and across your stone blocks until you reach your four blocks with the lever.

When placing your note blocks, make them one block apart so your redstone doesn't connect.

When its finished, when you flip your lever, the noteblocks should be making sound and redstone should flash