So i download an amusement park on this side and i put it into

MyDocuments/RCT3/Parks

But i'm playing the game and i can't figure out how to place the park into my game how do i place a theme park into the game

It might be a scenario instead, try putting it into "MyDocuments/RCT3/scenarios" and see if you can find it, if that doesn't work try putting it into MyDocuments/RCT3/startnewscenarios.

It might be a scenario instead, try putting it into "MyDocuments/RCT3/scenarios" and see if you can find it, if that doesn't work try putting it into MyDocuments/RCT3/startnewscenarios.

When i play the game where do i open it to lace in my park that's what i mean

You dont "place" a park. When you go to Sandbox mode, it'll be there in the Open Menu.

You dont "place" a park. When you go to Sandbox mode, it'll be there in the Open Menu.

It's not showing up still but it says the file is compressed while the rest say BAK file

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You dont "place" a park. When you go to Sandbox mode, it'll be there in the Open Menu.

It's not showing up still but it says the file is compressed while the rest say BAK file

You dont "place" a park. When you go to Sandbox mode, it'll be there in the Open Menu.

It's not showing up still but it says the file is compressed while the rest say BAK file

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You dont "place" a park. When you go to Sandbox mode, it'll be there in the Open Menu.

It's not showing up still but it says the file is compressed while the rest say BAK file

I would:
1. Download the file again and extract the entire folder again using peazip http://peazip.sourceforge.net/ make sure to download from the peazip.org button only (free I use it all the time
2. If you have a .dat and a .dat.bak file you usually need to place both files into Documents/RCT3/Parks
3. When you open up the RCT3 program go to the main menu. Play, Sandbox Mode, load game.
Note: If you can let me know which file you are using, I may be able to help you more.
I hope that helps and doesn't confuse you.
*Delete the old file before you install the newly downloaded one.*
*Make sure to take the .dat and .dat.bak files out of the folder itself before placing into Documents/RCT3/Parks*
4. If there is custom scenery you will need to know which items to download to use the file properly.