Hi there, I just joined the UG community and my names' Herb. I like to consult fellow musician about song tabbing on the guitar.

So lets' say I have figured out the melody line for a particular song, how do I know what is the related bass note. I figured a song wouldn't be complete and whole without the bass and melody notes being played together.

In short, my question is how do you know what bass note to add in a guitar tab. Help will be greatly appreciated. Thanks
You want to add the bass notes that are being played on the recording. If you're having a hard time hearing them, try using a mixer to bring them out. Your monitors/headphones play a role as well. There is a program called "Transcribe!" that uses pitch recognition software to help you recognize what notes are being played in a recording. I have it, and it has helped me in the past. If you're looking for a formula to determine the bass notes based on the melody, no such thing exists. The bass line is as much a creative part of a song as any other instrument line.
Thank you to both users.

I see, I thought that the bass note was derived from the chord played along with the melody line. For example, if a song had the chord progression G Am D C, then the accompanying bass note for the melody lines with be G A D C. Is this correct though?
That's one approach that will work, playing the tonic of the chord. As you get further into bass it can get a lot more complex.
And no, Guitar Hero will not help. Even on expert. Really.