Steps to change Blogger blog name and blog address:
- Login to your blogger account
- Go to Settings > Basic > Title: update your blog name here
- Settings > Basic > Publishing > Blog Address: Change your blog address here.
- Blogger will prompt if the blog address is available or taken.
- Once your get a blogger address that is available, click "save".
You are looking to use a custom domain to redirect your blog to a domain already purchased, you can also do that in the same area.