I hope that was typo, and you mean the v18.3, not the v14.3!
Go to the first post on page one of this thread. Look down about half-way, until you see the download links. The
BLUE text. Left Click on the blue text. Don't right-click it and use Save Link As... Just lclick on it once. I think that that step is where it went south on you.
A new tab will open in your browser, with the file you can download showing in the upper-right corner area. There will be a little box in the center of the page with a folder looking icon that says Download. Lclick it once.
Another new tab will open, with a box top-center telling you it "Can't be checked for viruses, Download Anyway?" Lclick on that. In other words, yes, download it anyway. Depending on your internet connection, it can take a while to download. Just let it run.
Once you have the zipfile on your PC, rclick on it, and unzip it with 7Zip to the folder of your choice. I'm presuming you know how to use 7Zip, or the program of your choice, to extract files from zipfiles. Make sure you extract ALL the files/folders in the zipfile to your chosen folder. I'm not sure, but I'm pretty sure Jimi put it all in an auto-installer. You should now have a file named Install.exe, or something similar, in the folder you unzipped to. Just to double check, I'm downloading it now to make sure this is all correct. I will let you know if there are any corrections I need to make

Rclick on the Install.exe file you now have, and select Run As Administrator. That is important. You will get a small window open up. This is the installer that will place the plane and all it's ancillary files for you. You will need to accept the EULA, as most programs require.
It will then ask you what you want to install, the plane, or the plane and the paint kit. I don't think you really need the paint kit right now, so ensure it's little check-box is NOT checked. Click Next.
Next, it will ask you where your FSX installation is. Like C:\MicrosoftGames\FSX, or D:\steam\steamapps\common\FSX. Wherever you may keep it. Use the little Browse button off to the left of the empty box to select your FSX root folder. Once you find it, it will appear in the white box. Makes sure it's correct, then click Next.
Let it run. After it installs the plane's files and folders to your FSX folder, it will begin installing the .Net Framework file. LET THIS RUN! Do NOT cancel it. It can take a while, and even APPEAR to be locked up. It's NOT. Just leave it alone until it finishes. When everything has finished running, it will ask you if you want it to open the Readme file included. Your choice at this point. The installer should now close.
You should now have the plane in your ...\FSX\Simobjects\Airplanes folder. If you want to verify it, look for a folder named FA-18C_FSXBA_BA_18.3.00. That's your plane. IN the sim, using the Aircraft Select screen, just select the "FSX Blue Angels and Groom Lake Productions" from the Manufacturer tab. That makes sure that all you see are the paints for this aircraft.
For now, I suggest you don't use the Blue Angel paints, just the regular squadron paints. It has to do with the cockpit lay-out, to prevent confusion, hopefully

Once you get used to the Fleet cockpit, the cockpit layout used by 99.9% of Navy/MC pilots, then you can use the Blue Angel paints to see the differences in the cockpit layouts.
I hope this helps a little. If I got too simplistic, I apologize, but you said you don't know computers. I was just trying to make it as understandable for someone like that. I certainly mean no insult whatsoever!
Good luck, and let us know how it goes for you.

Pat☺