This is one my body building buddy sent me, i'm also quite a skinny lad but have picked up a bit of weight since September. Appropriately change it round to your health and resources.

Workout A

Barbell bench press (2 sets)
Dumbell bicep curls (2 sets)
Lying dumbell tricep extensions (2 sets)
Cable pullback (2 sets)
Flys (2 sets)
Calf raises (2 sets)

Workout B

Squats (2 sets)
Barbell bicep curls (2 sets)
Seated dumbell shoulder press (2 sets)
Quad raises (2 sets)
Assisted pull ups (2 sets)
Assisted dips (2 sets)

Workout C

Deadlift (2 sets)
Lat pull down (2 sets)
Dumbell flys (2 sets)
Close grip z bar tricep presses (2 sets)
Assisted chin ups (2 sets)
Ham presses (2 sets)

Add an extra set when you can do 2 sets of 12, then add weight when you can do 3 sets of 12.

Nutrition wise, stay healthy and eat enough protein, if you weigh 80kg you should be eating 160g protein (xKG x 2 /1000).