# Install for linux or Mac OS users
# in your home directory, create a texmf folder

# that's if you don't already have a texmf directory
cd ~
mkdir -p ~/texmf/tex/latex
tlmgr conf texmf TEXMFHOME "~/texmf"

# that's for everybody
mv path/to/directory/gtbeamer ~/texmf/tex/latex #you need to change the paths of this line
sudo texhash #or sudo /usr/texbin/texhash