Assuming that you have already set up your Mac for Android development, you can follow these steps to debug your Amazon Kindle Fire app on Eclipse:
Connect your Kindle Fire to your Mac via USB.
Open Eclipse and go to Window > Preferences.
In the Preferences window, select Android from the left panel.
In the right panel, under the SDK Location section, click the Browse... button and select the location of your Android SDK.
Click Apply, then OK.
In Eclipse, go to Run > Debug Configurations.
In the Debug Configurations window, double-click Android Application.
In the Android Application window, under the Target tab, select the Manual option.
In the Connect tab, select the USB option and click the Apply button.
Click the Debug button.
Your app should now be debugged on your Kindle Fire.