Catenary of different types are in the spline section of objects, add along track holding "Crtl" key down for 1st section. usually best to place cat spline point over track spline point. Need extra spline joints on curves to look OK. Once you've done a few kms you'll get the hang of it! There are some cats on DLS but the inbuilt stuff is OK.
Have you seen the (literally) thousands of catenary masts, wires, support arms, counterweights, tensioning bits etc available on the DLS? How on earth does anyone understand the names of those things, quite apart from actually using them?