Visit the topic I created about that, for more information.
To OP:
Download a desktop version of electrum from its official website.
Create a new wallet with selecting "Standard wallet" and then "I already have a seed".
Click on "options" and then select "BIP39 seed".
Enter your seed phrase and click on "Next".
In the next window, click on "Next" again without chaning anything.
Enter a password if you want to and click on "Finish".
Go to electrum directory. (Click here to see default paths for different operating systems.
Open your wallet file and find "xprv".)
Go to electrum console. (If you don't see the console tab, click on "View" at top of the window and check "Console".)
Enter the following the command.
Create a new wallet in electrum. This time, select "Use a master key" and then import the xprv you got from electrum console.