Hi CrewDawg, first of all welcome to the forum! Second, please post problems with your add-ons such as this to the "707 - Report an Issue" section of the 707 - Pilots Lounge. Otherwise, your posts may be deleted or moved. But since your new I think they'll let you off.  

Okay, now for your problem. How did you download the livery, where and what's the name of the livery you downloaded (so that I can help you more).
Now, because you haven't told me much about your problem then read below and make sure you did everything as written:

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Your supposed to download new liveries in this folder: C://Program Files/Microsoft Games/Flight Simulator9/Captain_Sim/707/variants

Next, did you unzip all of the files downloaded.  To unzip the file once it has been downloaded, right click on it and click "Extract all" (It could be another name but similar to this)

Now, you have to make sure that all the files that have been unzipped are inside the variants folder and no longer inside the zipped folder. It doesn't matter where inside the variants folder.

Now, open the folder which should be named "Textures". Sometimes its inside another folder.

Once inside, make sure you have something called "description" (Most of the time its "notepad" program). If you don't, contact me and I'll make one for you. It doesn't take long to create it.

Now, open TCE and click texture.

click "select variation and the names of folders should come up.

Select the folder which is named "Textures"

Click okay and that's done!

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If you did exactly what I said above and it still doesn't work, contact me. Did you rename files belonging to the 707? If you did, well.... there's not much chance of it working. But try what I say and then tell me what happens. Don't forget to tell me the livery you downloaded.
Also, if you tell me your computer information such as the OS, processor etc. I might be able to help more.

Hope this helps!