"Now what do I do?"
You start off playing the root note. This will allow you to plod through any song without embarrassment. Here's 'Louie Louie';
http://www.chordie.com/chord.pere/www.b … nt=3824510
It's A D E D A all through the song but what does the bass play? Most obvious is;
------------------
------------------
----5---7---5----
-5-------------5--
This is dull but it's what I play if I'm singing the verse.*
To get 'Louie Louie' to rock you need to add passing notes. So the bassline becomes;
-----------------------------
------------------------------
---(4)-5-------------(6)--7-----5--
-55---------------------------
baBum-ba-Bum da-Dum-(ch)-Dum
Changing to this at the chorus really makes the song rock (at this point I stop singing, so I hope the rest of the band are up for 'Louie Louie, woaooao' not a hard lyric to remember). Remember the bassline is not set in stone, you can move around the A Dd D D# E shape how you like. You'll also note it falls over 4 frets, look to have your thumb and second finger on the 5th fret and use your pinky on the 7th (yep I know it's tough but that finger will get stronger).
Enjoy.
* There are other areas on the bass neck where A D and E are close together you could simply play the open strings but it sounds boring, if you haven't fretted a string you can't give it feeling. There's also a A D E two below and down but this gives a more treble feel. But once you've learnt the basic groove you could transfer to it for effect later in the song.
'The sound of the city seems to disappear'