Ultimate Preloader is a free wordpress plugin to create a preloading screen for your website before all your images (including the images in CSS) are fully loaded.
To install Ultimate Preloader
Login to wordpress (wp-admin).
In your admin dashboard click plugins and select Add New.
Type Ultimate Preloader in the search field and click Search Plugins button.
Install Ultimate Preloader.
After the successfully Installation click the activate Plugin link to activate the plugin.
[OR]
Download Ultimate Preloader wordpress plugin. Download link
Unzip and upload it to your WordPress wp-content/plugins directory.
Login to wp-admin. In your admin dashboard click plugins and activate the Ultimate Preloader wordpress plugin.
