Brand New to Dieting and Exercise

My name is Agnes.  I am a 45 year old female, looking to "get in shape" and just feel better in general.  I never had any weight issues really.  Im 5'8 and managed to maintain 130-135 lbs from about age 18 through my mid 30's.  Having my children to raise, kept me busy with just the normal day to day activities and chores which I considered my "exercise".  Now that they are grown Its only since then that I have begun to "add on" lol  Since my mid 30's to now, I have gone up to my present weight of 165.  Thats not alot - but I feel the difference and I dont like it!  So, for the first time in my life, I am attempting to do a calorie count and "Real" exercise ! Im starting with staying under 1200 calories a day and walking on the treadmill 30 mins in the morning and 30 mins in the evening.  I've been doing good, if you consider walking like I just got off a horse !  My legs are killing me, but Im determined to stick with it until my body gets used to it and stops hurting.  Im not sure what else I should be doing, I would like to tighten my arms and stomach, any suggestions for the "newbie" would be greatly appreciated.