First if you want to create a blog mainly a free blog, you should start by having an email account from Google ( Gmail i recommend). If you have one is okay but if you don't you should consider signing up from here.
After getting an email account then you should be ready to create a free blog now
Kindly visit WordPress.com or Blogger.com
These two platforms are well known for their good performance when it comes to creating a free blog i recommend them.
First Is How To Create A Free Blog With Blogger.
Goto Blogger.com (I recommend)
WordPress.com ( also recommended)Now if you are asking me which platform you should create your free blog with i will recommend if you are new into Blogging stuff you should consider starting with Blogger.com why because it is easy to navigate and mainly you can get approve on Google Adsense and other more.
Now these two platforms Blogger and WordPress.com both comes with a sub-domain names after creating a new blog.
What is a sub-domain name?
This is a domain that comes with the free blogging platform that you created your blog from which also indicates where you created your blog from.
Example of a free domain name is shown as: kellymarketingcpa.blogspot.com or kellybestonline.wordpress.com is an example of a sub-domain names
So once you create a free blog it comes with a sub-domain name as a new blog but i would advise you get a custom domain for your blog eg: Kellymarketingcpa.com.ng removing the blogspot so as to make your blog url very easy to input and remember for your visitors.
After all navigate to your settings and set up your blog title and meta tags after setting up a good description for your blog then what remains is a good and responsive template for your blog.
You can get a good template from this directories
* Blogger template etc
After installing a good seo optimize template, then you will have to customize it to your taste by going to the layout section in your dashboard.
In a free blogging platform like those that I have mentioned, no expenses will be done except when you are trying to buy a domain, all the hosting are free.
Note: This method is applicable for creating a free blog