Watch the Day 2 online guitar lesson by Ravi from Learn Guitar in 21 Days
You might be surprised to hear that there are songs that use only one chord! Experiment with both strum patterns, as you'll find some songs lend themselves better to straight downs, while others sound better with the down-up strum.
Also, it's normal for your fingers to hurt at the beginning. This will go away with practice, but that is also why it is important to keep our practice sessions short for now. Let's start making music!