First things first, make sure you've downloaded Electrum from the official source, and verify it using the GPG signatures. More information here:
https://bitcointalk.org/index.php?topic=5240594.0It's really quite simple, and you probably don't need (or want) anyone helping via a phone call. Not to mention, sharing a phone number is not secure or private. Here're the steps needed:
Once you've installed Electrum and launch it for the first time, this is what you'll see:

Click next then select "Import Bitcoin address or private key."

Click next, and enter your private key (or keys.) You can list as many keys as you'd like. Here's an example:

Click next, and then enter a strong password,

Click finish, and you'll be taken to the address's history tab.

Once you've reached this point, you can click on the "Veiw" menu and enable all the tabs you'd like to see. The "Addresses" tab will list all the addresses for the keys you've imported.

The rest should be pretty straight forward also. Go to your Coinbase account, and select Depostit > Deposit Crypto. Search for bitcoin, and select the Bitcoin Default chain. They'll provide you with an address. In Electrum select the "Send" tab, enter the address provided by Coinbase, and double check it to make sure the address hasn't been altered. Fill out the amount you want to send, and then click "Pay" follow the prompts and your bitcoin will be on it's way to your Coinbase account. Be patient, Coinbase requires six confirmations before they post your coins in your available balance.