Complete setup for your smart home device, using the manufacturer's companion app or website.
Connect the device to the same Wi-Fi network as your Echo devices.
Download and install the latest software updates for your smart home devices.
To connect a smart home device using guided discovery, in the Alexa app:
From the menu, select the Add Device.
Select the type of smart home device you want to connect.
Select the brand and follow the on-screen instructions.
To discover smart home devices using a skill, in the Alexa app:
Go to the menu, and then select Skills.
Find the skill for your device, and then select Enable. Follow the on-screen instructions to complete the linking process.
Ask Alexa to discover your device. Say, "Discover my devices," or select Add Device in the Devices section of the Alexa app. If there isn't a skill for your device or service, it may not be compatible with Alexa.
Have you installed the app and have it working with the plugs? The included manual (probably just a small folded page with tiny print) should cover that, and I notice the product listing even includes a brief description. After you have the app working and the plugs linked to your WiFi, you'll need to enable the Smart Life skill: