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.

AboZain Albanna

Customize Login Page is a simple plugin gives you the ability to make your WordPress Custom Login Page with your Logo and Your site theme

Customize Login Page

very good plugin , this is very good plugin to custom wordpress login page



Nice Work

Awesome

A simple, Customize your Login Page with your Logo and Your site theme

wp Custom Login vs Customize Login Page