If you do alot of cardio, ease up on it, do enough to keep healthy but forget the 2-3 hour bike rides until you put on some mass.
You've read about anabolic steriods? Did you know the best out the is in the supermarket? Like richard says, try to get a meal down ya every 3hrs even if it's a small portion. You don't need a giant portion every sitting (yet).
You can get a 5k tub of lean mass shake (carbs + protien) for around 30 odd quid, you can have a couple of these a day to replace a meal (easier to get down).
Try to get to a decent gym as you'll get great help there.
Good luck!!
eat eat eat
