HP Compaq Presario,Presario 1515 Supplementary Manual page 16

Use your chair to fully support your body. Distribute your weight evenly and use the
entire seat and backrest to support your body. If your chair has adjustable low back
support, match the contours of the chair's backrest to the natural curve of your lower
spine.
Always make sure your lower back is well-supported. Make sure it feels comfortable
in the position in which you are working.
J
Distribute your weight evenly and use the entire seat and
backrest to support your body.
Don't slouch forward.