If you search on the iTunes store for guitar lesson podcasts, they have some bass lessons on there. Im sorry but offhand i cant remember what the title of the podcasts are, but they are free, and around 4-5 minutes.
There are lessons on this site, and on Youtube, Avticebass, Cyberfretbass, and several others.
But I personally always recommend to go to a real teacher.
For long you live and high you fly
But only if you ride the tide
And balanced on the biggest wave
You race toward an early grave.

Ben Hamelech