Hi,

First little bit about me..
I am a patient of bronchitis, Using homeopathy as treatment.
I am a working guy.. who rarely gets up early in the morning.
I have done gym in my past under a trainer for 6 months only.

a) Can I do gym at night.. after 3 hours of taking food, as that's the best time I can have in my full day.
b) Is it a good idea, if I start it at my own flat by having my own stuff. As I know some basics have tips online.

Or it is like that it's an idiotic step and I should not.

Ta,
...

It's not a bad idea to work out, but you need to make sure you're starting your routine with the help of your doctor. Having medical issues, you might be advised to stay away from certain strenuous activities or chemicals.

Start small, don't bite off more than you can chew. And I have to ask what you mean in "b" when you say "by having my own stuff". Do you mean your own equipment?

Yes, you can work out at night.

The best time to work out is the time you will do it. And the best place is the place you will do it. If you have a home gym, and know how to use it, go for it.

Make sure you are working with perfect form (keep your weights low until you are absolutely certain of your form) and make sure you are working within your breathing limit. As you will have no spotter at home, pick exercises that can be done safely without one. Do dumbbell squats rather than barbell squats, for instance.

Also, make sure you warm up properly. For some reason, it's tempting to jump straight into the weights at home, but spend enough time getting sweaty and getting your heart rate up before you do. Bodyweight versions of the exercises you plan to do make good warm-ups. Also jumping rope or shadow sparring.

Check out ExRx (Exercise Prescription) on the Net for examples of how to do exercises properly and safely.

Both posters above are spot on...

When beginning to workout you must take the time to:

1) Develop a routine
2) Get your body ready to do this routine daily (don't jump right in and expect to swim)
3) Slow and steady at first. Start low weight, medium reps until you're body becomes accustomed to the routine. After that increase intensity.
4) Stay within your limits. If you have never been able to bench 300lbs, don't start now.
5) Medical conditions can/will hinder workout routines. Talk to your doctor, get advise, follow this advice.
6) Warm-up. Whether this is 10 minutes on a treadmill to get your heart going and too stretch your arms and legs. Never go into a routine stiff and rigid.
7) If a muscle is sore, don't work on it.

Can I ask what your goals of working out are?