Navigate into the wallet. Click on Wallet > Private Keys > Export. If you have your wallet file encrypted, it will prompt you to unlock your wallet with the password. A private key menu appears displaying all the wallet addresses currently associated with your current electrum wallet file and its corresponding private key in plain text. You have the option to export the file in a .csv format to use with MS Excel or in JSON format. Click on the file button and select the directory/path that you wish to export the private keys file to, then click export. Your private keys are the string of text that unlocks your wallet containing all your funds. It is very important that you DO NOT share or keep these keys in an unsecured location. It is recommended that you make a backup of these keys offline on a USB for safekeeping.