Go to "Addresses" tab and use one of the addresses shown there. All those addresses are yours. If you don't see "Addresses" tab, click on "View" at top of window and select "Show addresses".
You can also go to "Receive" tab and click on "New address" button. In this way electrum will show an address at right side of the window. That's one of addresses shown in "Addresses" tab.
Warning:
Before sending bitcoin to your wallet, make sure you have downloaded electrum from
its official website and you have the seed phrase (a series of 12 words) in a secure place.
Also, double check the address after copy-pasting that. There's a malware changing addresses to hackers addresses.