I just signed up to run my first 5k ...Run for Haven

The first time I ever ran I did a 15 minute mile. That was on January 8, 2012. Since I have been trying to improve my time but have only been able to complete in 16-20minutes. Mainly because of the pain in my knee. Today I am so stoked. I ran my mile in 14:05 minutes and there was a brief moment were I had to stop and tie my shoe. I feel so accomplished. I was being to feel I would never get back to the 15 minute mark. I need to keep moving froward cause I just signed up to run my first 5k. March 17 Tioga Town Center - Run for Haven - 5K. I need to Start planning now for you St. Patty's Day costume - the best costume at Run for Haven will win a prize! Any ideas please post.