Before you go for a bulking session you will need to become familiar with weight training and ideally perfect form on some key exercises whilst doing so.
I normally recommend doing the exercises below circuit style 3 times round 10 reps each as a beginners free weight session. Please do some research on correct form, this will be invaluable once you have got the initial section completed.
Deadlift
Bench press
Squat
Crunches
The weight shouldn't feel too heavy during this time, you should feel tired rather than straining during the workout, especially because it is a no rest circuit. The idea is to get perfect technique and familiarity with the performing these movements slowly and controlled. It is far better to find it too easy and slowly build up than overdo it and be incapacitated when your next session is due.
You want proper cardio warm up and cool down along with stretches, and this should be an absolute maximum of three times a week first of all, which will only be practical if keeping it light.
As you progress over time, you will be able to add weight but only gradually due to lack of rest time.
Once you have done this for around 6 weeks you will likely be ready for a more direct bulking session and will have learned some key movements that will serve you well always, especially deadlift.
I have come under fire before for giving beginners deadlifts in a session, this is considered an intense exercise and many blame it for bad backs. Reality is intensity will come from weight not the movement, and this will build strength into your back meaning it won't give you problems, if your form is good. The other reason I include it is this should always be the way you lift and lower a bar. I see many performing an exercise like arm curls, with impeccable form, then put it down by bending their backs, these will often be the same individuals who say deadlifts damaged their backs.
This is a suggested beginners session. There are others around. Which ever you choose, enjoy.
