Hello All,In order to install WordPress theme into your blog you need to perform below mentioned steps:
1) Download the theme on local system and extract it from the zip file.
2) Upload extracted theme files into your domain where you have installed wordpress.
Always upload this folder in the wp-content/themes of wordpress.
3) Login into WordPress administrator panel and go to the Presentation tab. Simply click on the theme which one needs to be activated and upon the click theme is activated.