There are several ways to get from one point to another in City Life.
1. Driving by Car
You can go nearly anywhere you want on the map. The only exception is the island on the top right. Yuu will have to use other Transportation to get there. I would stick to the roads while traveling as most cars will get stuck on the leafy ground inside the jungle (dark brown). There are some exceptions like the Ford F150 Raptor.
2. Flying by Helicopter
You can go anywhere with a Helicopter if you find a sutible landing area. Helicopters are quite expensive and require a Pilot License.
3. Calling a Taxi
You can call a taxi over the Mobile Phone. If you are somwhere that is reachable with a car, they will come with a car. If you are not rechable you will get picked up by an air taxi. See Taxi Driver for more.
4. Getting a Lift
Instead of calling a Taxi you can just ask other players to give you a lift.
There are several Subway Train Stations around the map. Open the booth, go inside and close the door. Then you can select the travel Option and go to other stations on the map. This will cost you some $$$. See Underground for more.
During Roleplay or Events players may drive a bus around. Just hop in and see where it will take you. See Bus Driver for more.