find the mass of a wire in the shape of the helix traced by (cost, sint, t/pi)

from pi to 3 pi if its density at each point is proportional to the distance from the point to the xy-plane

so i have mass= the integral from pi to 3pi of

cost + sint + t/pi dL

but i'm not sure what dL is..i saw it in an example in the book.

is dL the derivative of what i have above? or is it the magnitude? or do i ignore it?

after i clarify this, i think i'll be able to hopefully solve it..