Old country tunes are a real good start for playing bass! You best bet is to pickout the notes by ear and learn a few of the "classics" Youll notice alot of the older songs use the same chords/rhythms/positions. Goodluck!
Oh yeah...
G---------------------------------------
D---5-----5-----5-----5------4-5--------
A------5-----5-----5-----5-7------------
E---------------------------------------
and...
G-----------------------------------------
D------------------5----------------------
A----------5---7-------7---5--------------
E--3---7-----------------------7---3------
Those are some very basic lines that you can try for fun
Joe