The edition on Steam is the Gold edition. The Platinum edition has a few more coasters and the Vegetation designer for an advanced vegetation solution. Their proprietary technology allows players to build everything from grass to elaborate oaks. Trees are procedurally generated and can be controlled by custom wind and turbulence settings.
In order for you to have guests in the park, you have to press Test Park or Enter Park (see Screen Shot- Test park is green arrow and enter park is red arrow). You also have to have something for the peeps (people) to ride whether it is coasters or flat rides. Your paths have to line up with both the entrance and exit to the rides, or they will not go on them and the ride will act as if it isn't there.
When you use enter park, you are placed into the park in 1st person view, but if you roll the scroll wheel, you can be placed in 3rd person view. Hope this helps explain things.