First of all congratulations!! Trust me, you will do just fine!!
The Junior Deacon's position is a wonderful place to begin your journey as an officer. In fact that is exactly where I began my journey. The job is relatively easy at my Lodge, you'd be responsible for the flags outside, the floor in the narthex and Lodge room, putting the officers jewels out and setting other parts of the Lodge up before the meetings, and most importantly guarding the inner door. This is a time to really begin to learn your role as inner guard, sharpen your examination skills with the assistance of the Senior Deacon. This is a great position to meet new Brethren!!