Hey mcleja.

The first thing you should do is write down the equations to take you Euclidean to Cylindrical. From there you can then express things in terms of r and t (in cylindrical) and the cylindrical co-ordinates will be a function of r and t.

If you are confused with the r's and t's, just drop them and replace x(r,t) with x, y(t,r) with y and z(r,t) with z and after you converted to the co-ordinate system add the r and t back in.