To start learning your notes on your bass, start with the strings. Each string is a note and the frets after it represent a half step on the piano. The string notes are:
Fattest / 4th string: E
3rd string: A
2nd string: D
Smallest / 1st string: G
So, learn your piano notes first then learn them on the bass. I'll give you an example:
4th string is E, 1st fret is F, next is F#/Gb, next is G, etc. You see what I mean? Every half step on the piano is one fret on the bass.