As you can see I have themed my blog to match the rest of my site. I did this using child themes. Child themes work by having a parent theme they run off with an exception to any changes that you make to the child theme that will then overwrite the parent theme.
When making a child theme you can choose to link the child stylesheet to the parent theme stylesheet by adding @import url(“../parent-theme/style.css”); to the child style.css document. The other option is to start from scratch with the style.css file and write all the CSS by hand. I opted for the linking since it saves a lot of time and makes sure that no sections miss styling.
The benefits of using a child theme over modifying the original or parent theme is that when the theme gets an update from WordPress it will not overwrite all your designs. Because WordPress is always being updated with new features and bug fixes allowing theme designers to update their themes it is really important that you create a structure that can work for today as well as for the future.