No problem! Warming up is going for a quick, very slow jog before stretching. This is important, as stretching cold muscles is less effective than muscles that have been warmed up by jogging a block or two. Then you can do a few stretches. I just stretch the basics: quads, hamstrings, calves. I also stretch my hip flexors, since I've had trouble with them in the past. I like to start my run slow and build up to whatever pace I am aiming for that day. Injuries occour when you overuse an area or you transition to quickly from a resting state to a more high intensity pace.

Cool down is also important. I like to walk another block or two after finishing a run to allow my muscles to transition more smoothly to a resting state. Stretching is also important after running, as it releases lactic acid that built up during your run, as well as allowing blood to flow more effectively into those areas that you exercised and need nutrients the most. Stretching after you run is actually more important tha stretching before you run, believe it or not.