Cycling can be a very effective method for fat and weight loss. If you are going to be primarily using a trainer, then you will probably want to go with a time based method rather than distance.
If you are serious about this, I would look at investing in a powermeter of some kind. I would recommend a wheel based meter with ANT+ technology (Almost all powermeters anymore are ANT+), with a paired computer. The reason I state this is that power in watts x 4 is almost exactly equal to calories burned, due to the efficiency conversion of human power to bike speed/time. So if you cycle at 200 watts for 1 hour, you've burned ~ 800 calories.
The other advantage to this is that you can also pair your powermeter with an online program such as Trainer Road and get somewhat personalized training plans. (Note, I am not affiliated with TR, just a fan).
For the actual program, initially I would just aim for TITS (Time In The Saddle), and not worry about intensity. Get on the bike for at least 30 mins a day, more if you can stand it. After a couple months, you can start adding some intervals and speed work, and higher intensity/cadence work. The nice advantage is that cycling is much less impact than running, so you can do higher intensity more often.
You may find after a while that the trainer becomes boring, so don't be afraid to grab a helmet and head out on the road occasionally to keep things interesting.