Extract MySQL information from a compressed tar.gz file
Actually it seems a backup by copy files (as tables are myisam tables) not a mysqldump. So you just need to untar this compressed file by below command on linux-

$ untar -zxvf your_backup.tar.gz . 


Note: Please run this command from the directory where your backup file exist and it will provide you normal backup also in same directory.

Now you can simply copy these files (*.frm, *.MYI, *.MYD) to your database directory in which Database you want to restore them and it should work.

Note: if there is any permission related issue then use below command to make sure mysql can use these files/tables.

$ chown -R mysql:mysql /path_till_your_db_directory/*