I suspect the the full model number of your Kenmore microwave oven is 721.89940490. I do not find the installation instructions available online for this model. You may be able to obtain the installation manual by calling our Manage My Home Member Services Team at 1-800-803-6775, between 8 a.m. and 8 p.m. Central Time. They will be more than happy to help you track down the manual. If they are unable to help you find the installation guide online, you can order a hard copy from Sears PartsDirect
using part number 3874W500785.
I am showing that the wall template for installation is a separate part. I don't anticipate that it will be available online. You can ask the Manage My Home Services Team for help in obtaining this document as well. I'm not sure that they will be able to locate this item for you. This part is discontinued and no longer available from Sears PartsDirect. You may not be able to obtain the template for installation of this microwave.
If your full model number is different than the one noted above, resubmit your question with the complete model number off of the microwave for more help with installation information.