Importing your MetaMask account is simple and can be done in these 4 easy steps
1.) Open up your MetaMask app and navigate to the wallet you would like to add.
2.) Copy your public key (starts with "0x") to the clipboard [shown below]
3.) Navigate to your "Add Wallet" page, paste the public key in in to the address bar, type "ETH" into the Cryptocurrency box, and click "Add Wallet" [shown below]
4.) Repeat for all your MetaMask accounts you would like to track!