Check the following videos for how to mobilize the upper and lower body. If a particular area is tight from a previous workout, feel free to focus on that area for a few seconds longer.
Using a foam roller or a lacrosse ball is akin to self-massage. The objective is to relax tight muscles, increase blood flow, and remove mild tenderness from a previous workout. It is a great way to keep range of motion that you currently have. For more info on the use of foam rolling, check out the article series that starts here.