How to install a theme in LMMS

Download the chosen theme to your computer.
Unzip it as follows:
Right-click on the *.gz file (ex: default.gz), look for the "unzip to *.tar" option and click it.
The system will create a folder with the file name.
Open the folder and unzip the *.tar file in the same way you did with the .gz file and the system will go to a folder with the name of the theme.
Copy this folder and paste it wherever you prefer, I suggest you paste it in the themes documents\lmms\themes folder.
Open lmms and in the upper left corner click on Edit, then on Settings and then on the bottom button in the left column where
It has the design of a folder.
In the menu, look for Theme Directory, click the button next to it and look for the folder with the name of the theme, click Choose.
Click OK, close LMMS and reopen it.
That's just being happy.