Electrum automatically changes the address in the 'Receive' tab once you receive some coins to it. You can reuse it as many times as you want. If you see your transaction in the 'History' tab then everything is fine. Since you sent it to yourself, you should see that a small amount of coins has been deducted from your wallet (a transaction fee). You can see a list of your addresses by selecting 'View-> Show Addresses' and going to 'Addresses' tab.