Hey PlanetCoasterFan4, You can just select the building or ride and click on the save as blueprint on the ride / building menu (near the bottom). This will then save into your 'my blueprints' section at the bottom right of the screen (next to coasters).
This will then be in your file system.
Mine is under: C:\Users\owner\Saved Games\Frontier Developments\Planet Coaster\76561198047638014\Saves
Yours will most likely vary from this. But it will basically be like: c:\users\%username%\frontier developments\planet coaster
If you copy that and paste it into your file explorer or search function on windows, it should appear for you and you can navigate from there.