You can not buy Bitcoin on electrum directly, try to use an exchange to but the Bitcoin, then send to electrum. The fee can be very high, high. Also know that using decentralized exchange like Bsiq will give you more privacy. You can also try to create the topic on currency exchange board, you will probably see a seller, but make sure you trade with a reputed member and use a reputed escrow service. You can also buy using centralized exchange, but it will not let you have privacy, while sending bitcoin from such exchange do involves high fee to be paid.