From the Salesforce AppExchange, administrators can install Resource Hero in either a sandbox or a production environment.
From the Salesforce AppExchange, navigate to the Resource Hero listing:

To install in a production environment, click the Get It Now button then, after confirming your login information, click the Install in Production button.
To install in a sandbox, click the Try It button, then make sure to select the Try in your sandbox option. After confirming your contact details, click the Continue to Installation button.

Installation
Once logged in to your production or sandbox environment, you will be prompted to select the type of users that you want to install Resource Hero for.
Select Install for All Users if you plan on granting access to all users in your org, or, if you plan on managing security more granularly or with permission sets, select Install for Admins Only.

Click the Install button.
The installation may take a few minutes. You should receive an email when the installation is complete.