This is a WordPress theme gallery plugin that allows you to upload/download/manage any number themes on your blog.
(1) unzip the bm_themegallery.zip file in /wp-content/plugins
(2) Active the plugin
(3) Upload themes into database through Options >> BM Gallery in the Admin panel
(4) Create a place holder page (Write >> Write Page)
(5) Add a title (for example "BlogMechanics Gallery")
(6) Add a description (optional)
(7) Add a "custom" field named "bm_gallery_home" with value "true"
(8) Publish the page
(8) Add a link to the newly created gallery page from your blog.
(9) Add the "BM_ThemeGallery" widget to a sidebar. This widget is only shown when visiting the theme gallery.