Learning how to lay down a swinging/rocking boogie bassline is essential for any rock bass player. Please take note of the rhythmic instructions at the upper left hand corner of the chart. This tells you that although the eighth notes are written normally, they're played as a triplet figure with the first two notes tied to achieve a "swing" or "syncopated" feel. There's varying levels of how much "swing" you feel, and a lot of that is determined by how much you emphasize the downbeat and lay off the second half of the beat. Experiment with different levels of swing feel to see what is appropriate for the song, which should always be the main goal of any bassist.