First, install MetaMask for Chrome. Then, click the Chrome Extensions icon (the puzzle piece) and select MetaMask. Within the MetaMask window, click "Get Started" and then "Create a Wallet".
See more: What is MetaMask?
Set a wallet password and click through the rest of the setup screens. When finished, you should have a new empty wallet as shown below.
Next, select the network dropdown at the top right of the MetaMask screen.
From the dropdown list, select “Add Network” and enter the following:
Network Name: Milkomeda Cardano (C1)
New RPC URL: https://rpc-mainnet-cardano-evm.c1.milkomeda.com;
Chain ID: 2001
Currency Symbol (Optional): MilkADA
Block Explorer URL (Optional): https://explorer-mainnet-cardano-evm.c1.milkomeda.com
Click “Save”, and you should now see "Milkomeda Cardano (C1)" in the network dropdown.
Alternatively, you can go to this website: https://chainlist.org/chain/2001 and click on “Connect Wallet” to add Milkomeda C1 Mainnet to your Metamask wallet.