A theme changes the way your website looks without changing the content in any way. WordPress themes can also provide other features, but these differ from theme to theme.
Your WordPress site comes with four themes pre-installed, which are:
- Twenty Thirteen
- Twenty Fourteen
- Twenty Fifteen
- Twenty Sixteen
There are two ways to install a new theme in WordPress. The easiest way is to install a theme through your WordPress Dashboard or you can upload your own theme.
Installing a theme in the Dashboard
To install a new theme go to Appearance > Themes > Add New then use the Search or Filter options to find a theme you like the look of.

Click on Preview to see how the theme will look on your site or click Install Now to install the theme to your site. Once the theme has installed you can then click Activate Theme to set your new theme as the active theme.
Installing your own theme
If you downloaded your theme from somewhere else you can upload it in .zip format. To upload a new theme go to Appearance > Themes > Add New > Upload Them.

Click Browse to find your theme and then click Upload.

Once the theme has uploaded you can then click Activate Theme to set your new theme as the active theme.
Congratulations, you just installed a new theme.