Try one of these articles:
The Firefox Marketplace has apps designed for your Firefox OS device. We'll show you how to find and install them.
Access Mozilla Services with Firefox Accounts
Firefox Accounts is a safe and easy way to access Mozilla Services on all your devices. Learn how to create an account and access services by signing in.
This article describes how to uninstall an application on Firefox OS.
Recommendations in Marketplace
The Firefox Marketplace now recommends apps that you might find interesting. Learn more about how the recommendations work.