I need help gainin access to my site again

I was trying to change the url of my site, I mean like completely change the url.( from http://www.sourceful.co.uk/ to http://thestatusof.com) I had already previously forwarded the old url to the new one but I decided to watch a youtube video on how to change it.

So I went to the settings tab in the wordpress admin site and changed both of the url sections to http://thestatusof.com and saved it. After I did that it gave me an error and I tried to refresh it and it logged me out. I have tried to log back in and it won’t budge. I am not receiving any notice stating the user or password is wrong all it does is refresh and clear the contents out of the sections.

Someone said I would have to do this but I don’t know how to.
1. set the new domain up on the hosting
2. make a backup of all files on the old domain (sourceful)
3. Make a MySql dump of the sourceful website
4. Once the new domain has been setup on hosting, upload the backup file to the new domain
5. Go in to the MySql server and run a query.
6. You will then need to edit the config.php file to match the new host details

I have also tried a number of the methodes on this one http://codex.wordpress.org/Login_Trouble and this one http://codex.wordpress.org/Changing_The_Site_URL

Honestly I do not know what I am doing so I probably messed something up even more. Before this happened I somehow mess up the theme. So I need some serious help with this.