plz help

Are you asking will you have an easier time learning bass guitar having a knowledge of 6 string guitar first? If so, I would say it will certainly help. Assuming standard tuning for both the 6-string and the bass, the strings on a 4-string bass are tuned to the same notes as the lowest 4 strings on your 6-string guitar: E, A, D, and G from low to high. The bass guitar has a longer scale length, however (the neck and the strings are longer) and the strings on the bass are much thicker, so the bass guitar plays in a register an octave below the bass strings on your 6-string. The bass is nice because the 4 strings are tuned symmietrically. There is a musical interval of a perfect 4th between each string. On 6-string guitar all of the intervals are a perfect 4th except the interval between the G and the B strings which is a major 3rd. The asymmetry has caused me some difficulty with learning 6 string.

You will notice some major differences between guitar and bass, however. One is the longer scale, which makes the distance between the frets greater and requires considerably more finger stretch in the lower part of the neck. You will also need to decide if you want to use a pick or play the bass fingerstyle using 2 fingers. If you are used to playing guitar with a pick, learning fingerstyle on the bass will take a bit to master.

The guitar is more geared toward playing chords. Chords are not nearly as commonly played on bass since multiple low-pitched strings played simultaneously sound "muddy". When chords are played on bass guitar they are arpeggiated with the chord notes played individually in rapid sequence. The focus on bass guitar is more geared towrds maintaining "the groove" which requires a very good sense of timing and the ability to play in lock step with the drummer (if there is one). If there is no drummer, then the bass player becomes the timekeeper. The bass also provides focus for the root notes of the chord sequences and often frees up the lead instruments from having to play the root notes.

I think bass requires a greater knowledge of musical intervals and chord structure than guitar. With the guitar you can go a long way by just memorizing fingering patterns for the various chords. With bass, you have to not only know the chords in the progression, but have to be able to immediately find the roots, the 3rds, 5ths, 6ths, 7ths, 9ths etc of each chord.