The given curve is rotated on the y axis. Find the surface area.

$\displaystyle y = \dfrac{1}{4}x^{2} - \dfrac{1}{2}\ln x$

Interval: $\displaystyle 2 \leq x \leq 5$

How can I convert the "y =" function to an "x =" one, or is there some special way? Also, the interval has an x in the middle, but if were rotating on the y axis, then it should have a y.