Take a look at the documentation.
Quick-Start
If you just want to get started without reading more in-depth information, follow these basic steps:
Unpack and mount your switch (desktop or rack mount) and power it on.
Plug any one of the Ethernet or fiber ports into an upstream device on your LAN. The uplink port should have access to a DHCP server and it will also need to be able to communicate with the internet.
After powering on, your switch will download the latest software. While upgrading, the switch's power LED will flash green/white. Once the switch has checked into the dashboard, the LED will turn green/white. Note: A solid orange light indicates that the device has not checked in with the dashboard yet.
Log in to http://dashboard.meraki.com (For any devices that are used in mainland China, please visit http://dashboard.meraki.cn and create a new network. If you do not yet have a dashboard account, choose "Create an Account") Type in the serial number of your switch (found on the back of the unit) or simply enter your order number. This will create a new switch network.
Make your desired configuration changes under the Switch > Configure section of the dashboard.
For additional switch installation information, please refer to the MS Installation Guides article.
https://documentation.meraki.com/MS/MS_Overview_and_Specifications/MS120_Overview_and_Specifications
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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