Watch the Playing a Pattern online guitar lesson by Stu Hamm from Learn Bass 1: First Steps for Beginners
The great thing about playing bass is that all the strings are tuned in 4ths. Since they're consistent, if you learn a pattern or position in one key, all you have to do is move it around the neck and you can play the same pattern in any key, just by moving your hands.
Let's talk about a hand position for a basic blues pattern. We're going to play a blues in A, starting with the A at the 5th fret. Next, we'll play two bars of D, just moving one string down. Then, we go back to the A. What we play next is called a 5th (V), which is an E. We then go back to the 4th (IV), which is the D. We end by going back to the I, which is the A.
Now that you understand the blues form and pattern, let's try playing it slow at first over a metronome, then faster with the band!