To change the current theme of your WordPress website, login to your WordPress dashboard and proceed as follows: (Added numbers-1 and2)

• From the left hand side pane, select Appearance.
• Click on Themes, then take one of the following courses:

Selecting a theme from Pre-installed themes

• By default, there are three themes already installed in your WordPress.
• To select from them, click on one of the themes.
• Click Live Preview to see how your website will appear with this theme.
• (Note: You can further customize its appearance on your website, either before or after the installation of theme)
• Click on Save & Activate to start using the theme.

Selecting a theme from Non-installed themes

• Click on Add New Theme.
• New page opens up that lists hundreds of WordPress themes to choose from and that are classified under three categories – Featured, Popular and Latest.
• Select a theme of your choice.
• Click on Details & Preview to see a preview along with some important information about the theme.
• Click on Install from top of left side pane, to install it on your WordPress.
• Now, follow these steps to activate it. 
• Click On Appearance.
• Click on Themes.
• Click On Select Theme.
• Click on Activate.