I will try to make this simple for you.
1st Delete existing libreoffice as in post 12.
2nd If you are installing from the downloaded .deb, which it appears you are, you need to either CD to the directory of the .debs or install a program called open-terminal: (recommended)
You may need to logout/in for it to take effect.
sudo apt-get install nautilus-open-terminal
3. Go to your downloaded .deb which is probably a .targz file. Right click it & "extract here"
4. Enter the .deb that you have extracted, inside there are 2 folders, enter the DEBS folder, then click "file" & "open in a terminal".
5. In the terminal type the command:
Wait for all the .debs to install.
6. Go back to your .deb folder & enter the "Desktop-integration" folder, click "file" & "open in a terminal" again.
7. Again type the command:
It' probably best to logout & in again at this point, but LO4 should now be installed.
All the instructions are in this tutorial:
As far as a degree in rocket science goes, we probably all felt this way at one time, but bear with it, it does get easier, I promise.