1.Sign up on musical classes or musical schools
2.Search out the web and find free lessons and tips (there's free lessons and teachers who do practice instruments online for almost any instrument)
3.Also you can search for simulate models of bass on net.
4.Buy a cheap bass guitar, give your soul to it, play, practice, mess up, practice more, repeat, mess up again! Then practice, practice , practice till you get it right and out of the sudden you find yourself a pro.