Long story short is that the Foam Roller is vital for stretching your muscles and preventing injury. I have a small travel size one because I live in a small apartment but the longer ones are great too. There are tons of videos on YouTube about how to use the Foam Roller. If you are a beginner runner or even advanced and don't have one, I recommend buying one! It is well worth it.
I made a little video using a Vintage Video Maker app (thx Reagan for showing me this!) on my phone. Really I just wanted to experiment and I didn't have anyone to help me so please forgive me for the poor footage(my head cut off in the beginning) and it being a silent video, I am talking but all you can hear is the music. But to see more informative and longer videos go HERE.