Niaj Morshed

Just Install the plugin, then you can see the login form has changed, 
after this go to the Settings->custom-login & put your logo & background image link which you want. 
Enjoy.

wp Custom Login

This plugin can changes the logo & background image of the login form.

uberweb

View the plugin page for more information and discussion: <a href="http://www.uberweb.com.au/uber-login-logo-wordpress-plugin/" rel="nofollow ugc">http://www.uberweb.com.au/uber-login-logo-wordpress-plugin/</a>
Uber Login Logo is a simple plugin I made so that I could customise the login screen on my own website by utilising in-built WordPress functions and the WordPress media uploader. 
Considering all the bloated plugins and resource intensive implementations floating around, I thought this lightweight codebase and clean UI could be of similar benefit to other WordPress users/developers. 
Don’t expect too many fancy bells and whistles, this plugin does one thing, and does it well.

Uber Login Logo

Simply perfect

A simple, lightweight WordPress plugin to change your login logo.

wp Custom Login vs Uber Login Logo