How to lengthen my stride?!?

You need to simple reach out a little bit farther with the leg that you are stepping with. To help do this you should pick your knees up higher and drive your arms more. You can keep your current stride and increase your pace to accomplish covering more ground in a set period of time. Keep in mind that your legs will only move as fast as your arms are. So if you barely move your arms your legs will stay close together and if your pump your arms correctly your stride length will increase. Good Luck.