Once you have your buttons designed, you will need to upload them to an image site (such as imgur), which will generate code for your image.
Next, you will need to decide where you would like to place your buttons. I put my button bar right under my header (click where it says Add a Gadget, as shown in the image to the right).
I entered the following code to create my buttons:
The green represents the link you will put in. So if the button is for "home", you will enter the code to your homepage.
The blue is the link from imgur, where you uploaded your image.
To create the 6 buttons, I entered this code 6 times, one right after the other. I then entered the specific links needed for each button. The buttons should line up side by side once you have done this.