OK so having a pencil-neck is teh suxxors. And makes us look less male. Another area that's distinctive between male and female bodybuild is the traps, those muscles that go between the shoulders and sides of the neck.
Exercise can help and can do a trememous lot, short of going on T. Even after T, these are good areas to work on.
For the neck, my neck workout consists of lying on my back with my arms around so that my hands are between my lower back and the floor, so that I'm resting on them and my elbows to have my upper body at about 45 degrees. Then I simply move my head backwards, and then forwards, that's one "rep" or repetition. Try doing 10-25 to start, you are using the weight of your head to exercise your neck muscles, and at first you wil kick your butt! I do 50.
Then in the same position, keep your head straight but "nod" from side to side, I've heard firemen do this one. Don't overdo the rotation but try for a good range of motion, again this will kick your butt so try 10-25 reps to start. I do 50 immediately after the 50 of the earlier ones.
Then, I lay back on the floor, and do "bridges" using my feet and head as contact points. Normally, bridges are feet and shoulders as contact points. I do 20. DO NOT do these at first! You will probably hurt yourself! Instead, from a sitting or standing position, simply hold your hands interlaced on the back of your head and push backward with your neck, the idea is to exercise the muscles on the back of your neck.
I finish by doing 15 or 20 reps of putting my forehead on a weight bench, with my hands on there too so I can modulate the difficulty easily and not hurt myself, basically this is head-nods using the muscles on the front of my neck to support my body. These are ADVANCED you can do just fine with the first two exercises for YEARS.
All this, to end up with a slightly less pencil thin neck!
There are neck exercises done by wrestlers, martial artists, etc out there too. I think my routine is good but you can tailor something for your own needs.
I'm the only guy in my gym who exercises their neck! I figure if the added strength protects me in one accident etc it's worth all the work, and meanwhile I have a more manly neck!
Advanced bodybuilders also work their necks - I mean contest guys, the real serious guys, they work everything.
Now the traps. Those are thanfully, easy. Just pick up a weight or even a heavy suitcase ect and "shrug" it upward. You may be able to do anything from a few to 20 or more reps depending on the weight. Switch sides and do the other side. You should see results quickly, in that way it's much more rewarding then the neck work which you'll feel all right but it's hard work for little visual results over time.
The main thing with any training is consistancy. If you're not doing an exercise routine, then work these into your TV watching time, just before bed. something like that. If you always watch Spongebob Squarepants, and all the cool people do, then make that your exercise time. Or the morning news, or CSI, or when you listen to a certain show on the radio, etc.
Hopefully this helps out, I'm happy to answer any questions.