First off, we need to fund our previously created address with some bitcoins in order to make the first transaction. Thankfully, in the testnet we can use a free funding source called a bitcoin faucet, which provides worthless bitcoins for testing applications.

For this example, browse to the online faucet website at http://bitcoinfaucet.uo1.net/ or any other bitcoin's faucet websites, and get a few by providing the first address generated by Electrum and the address created by Bitcoin Core, as shown in the following screenshot: