Smoke: Welcome! Hopefully, I can give some direction, and then let others tear it apart:
Cardio:
If adding some mass is your goal, then the less cardio the better. None at all if ideal, but for health reasons, maybe 20 minutes 3 times per week is OK, and it's preferred that such cardio not be steady state/constant pace, but be interval style (e.g, after a warm up, do 30 seconds at a harder pace and then a minute or so at an easier pace). That is good for cardio benefit in a shorter time period, as well as for preservation of muscle mass. (Marathon runners don't look too muscluar, do they? On the other hand, look at sprinters.)
Diet
For bulking, adding mass, you need to eat (and probably gain a little fat along with the muscle). You can play it by ear, and keep eating until you see gains (perhaps, a pound --or more -- per week.) Even better is to get a handle on you caloric needs and plan you diet accordingly. Lots of people find they must keep a food log to maintain a handle on diet, whether for gaining or losing weight. You can buy a program, or use a free online version at
www.fitday.com . Also, you might read some of the articles at
www.johnberardi.com; he is one of the main gurus on how to eat big enough to get bigger. Even if you don't follow his specific plans of combining foods, you'll get the idea.
Lifting:
Have you been lifting? If not, then anything will help. If so, then what have you been doing? The general advice you'll get here is to:
1. Use a program designed by a pro (lots 'n lots of free ones available). There is a great overview and linking to programs in this topic on this forum:
http://forums.jpfitness.com/noncgi/u.../t/000056.html
2. Focus on heavier, compound movements/exercises. So, squats, lunges, deadlifts, overhead presses, chinups, pulldowns, rowing, etc. They stimulate the most muscles and hormones. Training those movements, and training then heavier, will help to build the strength and size. With those two goals in mind, your rep range will be 3-8 or so; not much 10-15 reps, but that can be OK to cycle in every now and then. Generally, no isolated movements (curls, leg extensions, etc).
That's my quick summary answers. Others can add in their thoughts.
FYI, A recent book and web site, "Scrawy to Brawny" is a good program which lays out an exercise routine and diet program. It was put together specifically for thinner guys who want to add some muscle onto their frames. This forum also has a "Scrawny to Brawny" topic going for guys who are following that.
Best wishes!