First of all you need to download the theme installable file from your account that purchased item, go to your Xtratheme.com > My Account > Downloads Button
Now go to your site Dashboard > Appearance > Themes and click on Add New Theme like below
Now click on Upload Theme
Choose zipped file that you have Downloaded from ThemeForest and click on Install button, then wait for installation process
Final step click on Activate theme
Theme Installation via FTP
- Log in to your server via your FTP software ( FileZilla, Transmit, etc )
- Unzip the theme-name.zip file, ONLY use the extracted theme folder pack.
- Upload the extracted theme folder into wp-content > themes
- Activate the newly installed theme by going to Appearance > Themes
- Go to Appearance > Install Plugins and install all plugins
- Simply click the Install button on each plugin to install them
- Done