Adding Image and text to the page after user creates account


I use remove Email Verification plugin. Once the user creates his/her account, it displays the page as attached with this thread.

1. How do I center the content ?

2. I would like to add some more contents like "Thank you message along with images"

Where should I edit the code,since I am using Remove Email Verification Plugin bit confused to find where to edit it.

Please help me.