Using the bass guitar
Use your computer keyboard or click on the bass guitar strings to play the bass guitar. The four rows of keys on your keyboard correspond to the four strings on the bass guitar.
Click "Highlight" above the bass guitar to show note names. Click "Mark" to mark notes on the fretboard when clicking on them. Hold down the alt key on your keyboard to mark notes with ♯ instead of ♭.
You can save your markings on the bass guitar by copying the web address in your browser window. This also allows you to share your markings with others. For example, here is a A major scale and the bass notes for the song Bitter Sweet Symphony.
Online bass guitar tuner
Click the "Tuner" button to activate the tuner. Click the first string you want to tune, and play the similar string on your bass guitar so that the two notes sound at the same time.
If your string is slightly out of tune, you will hear a pulsating sound between the two notes. As you tune the string, the pitches get closer and closer and the pulsation slows down. When the two notes match perfectly, the pulsation will cease and the two notes sound as one.