Without the model number, I cannot see the exact type of Kenmore 90 Series dryer that you have. There are several different types and models. The images below show the procedure for accessing and replacing the drive belt on the 2 common types of Kenmore 90 Series dryers. It is likely that you will be able to use one of these basic procedures. If you have a dryer like the one in the second image (lint screen in the door instead of on top), you may need to pull the plastic end cap off of each side of the console to find screws that secure the console to the top panel of the dryer.
If you need more help, resubmit your question with additional details and the full model number of your Kenmore 90 Series dryer.