vacuum line

Hello. I am trying to clean my engine and other parts associated. I have read in forums and found a product called SeaFoam. It says to use it through the vacuum line. Can anyone describe or if possible post some pictures of where the vacuum line is on a Ford Explorer XLT 1998. 4.0L.
Thank you

Look on the emissions label under the hood. It should give you a diagram of all your vacuum lines.