WordPress.com provides you with over 70 different template themes to choose from for your blog which allows you to pick an individual look and feel for your website. In order to access this part of the WordPress through your dashboard all you need to do is click on Appearance > Themes.
If you are familiar with how to use CSS, WordPress.com allows you the option of upgrading for a minimal fee to “Custom CSS”, which allows to gain access to the CSS Editing component under the Appearance menu section, therefore giving you a lot more control over the look and feel of your blog.
Themes and theme options are very limited in WordPress.com and is the reason why many people decide to get a WordPress.org account instead due to the freedom and flexibility that WordPress.org provides allowing you to upload your own themes and choose from over 400+ different ready-made templates.
What are Themes?
A WordPress Theme is a collection of files that work together to produce a graphical interface with an underlying, unifying design for a blog. WordPress.com currently has a very diverse collection of over 70 gorgeous themes (and we’re always adding more!) which you can easily preview and activate from the Appearance -> Themes area of any blog’s dashboard. You can change your themes at any time. If you do not see the Appearance menu option, this means that you are not an administrator on the blog.