This page of the guide to Car Mechanic Simulator 2021 describes exactly how to get to and around all the places you can visit in the game.
The Map is available in the wheel menu, if you pull it up with the cursor on the surrounding objects - not on the car.
After pulling up the map, simply select a location by clicking the list on the left. Some locations will be unavailable at first. You have to get to the right level first before unlocking them.