Hi... We live in a ranch home no basement. Want to add a water filter to our home one problem we have no idea where main water line comes into the home, everything is in the attic water heater,ac,heater etc. We know where it is on the street but not how to tell where it is in the attic or if it is even up there...

I live in the same type house. This is called a "slab house". Walk around your house and you will see a pipe coming out of the ground, sometimes with a hose bib on it, and that's the water coming into your home.
If that doesn't work for you the house shut off is located where the water enters your house and is located upstream from any of your fixtures. If you still have a problem click on back and we'll look farther. Good luck, Tom

Look around your hot water heater for a water line with a shut off valve and a pressure reducing valve.