The file goes in My Documents/RCT3/Coasters. Then in RCT3 goto the build rides sub menu and there should be a button that looks like a wrench(or something like that) A box will popup and click search(for something like that) and the coaster should show up. It'll take a while because the program searches the entire drive

were wil it show up?

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You don't convert .trk files to .ovl files. You save the .trk file in: My Documents\RCT3\Coasters. You don't need to convert .trk or .ovl files.

when i search in rct3 i put my files in the document/coasterfile but when i go into rct3 i search and it said 0 trk files found

Just to clarify...is this a custom track? Or, a track someone made and uploaded it to this site as a .trk ?
If it's an in game track you shouldn't have an issue to find it. If it's custom track let's say for example a B&M Sitdown by Parallax (most commonly used) I would recommend downloading that custom track (ctr) link http://www.customscenerydepot.com/index....;down=1465 and follow the instructions on how to install it.

If you can let me know which track you are trying to use, I can take a look and maybe get a better idea of what's going on.  

You don't convert .trk files to .ovl files. You save the .trk file in: My Documents\RCT3\Coasters. You don't need to convert .trk or .ovl files.

ok: now in CTR creator I have the .ovl files but no .trk files.  How do I go about creating the .trk files so I can actualy use my coaster.