As a Wealthy Affiliate member you have the ability to choose from thousand's of great Wordpress themes.
And that is actually very easy and it is done in a few steps.

Browse through the available themes and find the one you want to change your current theme with.

Click on details and get the themes name, copy it, and head back to the dasboard and click Appearances and Themes.

Type or paste the themes name into the searchbar and when the theme appears, hover your mouse over it and click install.

When the theme is installed, click Themes again and hover over the theme you just installed and click activate.

Congratulation, you have now successfully installed a new theme and changed your current theme. Next, we will have fun with customizing the Wordpress theme, you know, change some colors and add some new features, sidbar widgets and so on....so stay awake for a while more.