Step 1. Add your wallet address and send the request.
Step 1. Go to your twitter account and make a tweet with your ETH address (can be done with a Facebook post, too)
Step 2. Copy your tweet’s URL, paste it on and click the “Give me Ether” button. You can ask for up to 18.75 ETH
If you have problems with the first two options you can ask the community to send you some testnet ETH in the #rinkebyproblems channel in Discord.
Just send your wallet address to the channel.