Unlike most other wordpress users, i dont really know much about html coding and such, But........................
i did figure out how to change the wp login image from your login, registration and forgot password page, without using another plugin which id think would help keep load speed high!
so heres my Dum Dum guide
1. locate the image logo-login.png ( wp-admin/images )
2. second design your own logo roughly the same size and name it logo-login.png
3. use a ftp client such as filezilla to delete the old file and then upload your new logo
This works great but if id have to guess when ever you get the next wordpress update it will probally go back to the old image and you will have to do it again
Seeing as loads of people have been helping me out thought id post this for anyone who had this issue aswell