I think I can help.
Just so you, I was 5’11” and wrestled in the 119 weight class. I was skinny.
I am now (still 5’11”) weight 175 pounds and I have the same percent body fat as I did when I was 119. The two things I did were
1) Lift weights
2) 2) eat ever three hours
3) Drink LOTS of water.
As far a weight lifting, stick with basic movements. Squats, Bench Press, deadlifts. Have a powerlifting coach teach you these movements. I do not have much faith in the personal trainers I have seen at most gyms. Start slowly and with light weights, but to gain size and streght, you will have to lift heavy weights. I still love to cycle. But when I finish a long ride, I not only worry about carbohydrates, I think protein also. So I may drink ProPeptide MBF which has Protein: 42g, Carbohydrates: 84g, Fat: 5g. You can get it: http://www.dpsnutrition.net/get_item_dr008.htm
As far as eating, I strive for 1 gram of protein per pound if body weight. So at 145 pounds, try to eat around 145 grams of protein per day. Eat LOTS of fresh vegetables.
From Dr. Berardi site:
1. Eat every 2-3 hours, no matter what. You should eat between 5-8 meals per day.
2. Eat complete (containing all the essential amino acids), lean protein with each meal.
3. Eat fruits and/or vegetables with each food meal.
4. Ensure that your carbohydrate intake comes from fruits and vegetables. Exception: workout and post-workout drinks and meals.
5. Ensure that 25-35% of your energy intake comes from fat, with your fat intake split equally between saturates (e.g. animal fat), monounsaturates (e.g., olive oil), and polyunsaturates (e.g. flax oil, salmon oil).
6. Drink only non-calorie containing beverages, the best choices being water and green tea.
7. Eat mostly whole foods (except workout and post-workout drinks).
For more info check out these links. I am a big fan of Dr. John Berardi. I have made great progress following his advice.
Some may disagree. And if you are into racing, you may not want all that extra muscle weight to drag up the long climbs. It is what worked for me.