You should follow the themes installation procedure, but normally it should go something like themename/index.theme
. Ex.
$ ls /usr/share/themes/
Adwaita Industrial MurrinaCrystal MurrineRoundedIcon
AgingGorilla Kiwi MurrinaCrystalCurve MurrineRoundedLessFramed
Albatross Metabox MurrinaCrystalHuman MurrineRoundedLessFramedIcon
Ambiace Precise Mist MurrinaCrystalLine Murrine-Sky
Atlanta MurrinaAquaIsh MurrinaDark NOX
Bluebird MurrinaAzul MurrinaEalm Orangine
Bright MurrinaBlau MurrinaElement Raleigh
Clearlooks MurrinaBleu MurrinaFancyCandy Redmond
Crux MurrinaBlu MurrinaGilouche shearwater
Default MurrinaBlue MurrinaLoveGray Shiki-Brave
Emacs MurrinaCandido MurrinaNeoGraphite Shiki-Colors-Easy-Metacity
Esco MurrinaCandy MurrinaVerdeOlivo Shiki-Colors-Metacity
greybird MurrinaCappuccino Murrine-Gray Shiki-Colors-Striped-Metacity
greybird-compact MurrinaChrome Murrine-Light Simple
HighContrast MurrinaCream MurrineRounded ThinIce
$ ls /usr/share/themes/Adwaita/
backgrounds gtk-2.0 gtk-3.0 index.theme metacity-1
The same for your ~/.themes
directory:
$ ls .themes/
Adwaita-Dark Darkair
$ ls .themes/Adwaita-Dark/
index.theme gtk-2.0 gtk-3.0
When you extract the files, should be like that.