So, you wanna know about playing bass, eh? Well, you might be in the wrong place anyways, but I'll see how I can help ya. Bass is pretty much the rhythm keeper in the band along with the drummer. It helps hold everything in place in music. (Thinking of more as I go)
Methods of playing
There's different ways to actually play the instrument. You can (quite obviously) play by pick, which is the universal strumming tool to use. You can also play by thumb, which gives the note a heavier feel than with a pick, and it doesnt make a scratching sound on the string. Or, my favorite method, use your fingers (specifically pointer and middle). It's easier and the notes (to me) come out better by finger than by thumb.
Methods of learning songs
The easiest way (in my opinion) to learn songs is by tabs. It shows on the tab an image that represents the neck of the guitar with numbers going across it. The number represents the fret on the bass. If you can't read tabs that well and have a real good sense of hearing, then u could also learn a song by ear. That basically means that you can figure out what to play just by hearing it instead of reading tabs or sheet music.