Given the vagueness of the question I'll ramble a vague answer:

Reproducing light sources in blender (or in any photographic device) is a bit problematic: in order to get the level of brightness that we associate with them perceptually the emitters get so bright that they are just white with no detail.

[![enter image description here][1]][1]


Or if we want to get the detail on them there is not enough light on the scene
[![enter image description here][2]][2]



(more on the subject on [this question][3])  


The shadows produced by the glass can be less dense if you increase the samples and the number of bounces for transparency and transmission (note that your rendering time will increase dramatically)


[![enter image description here][4]][4]


Another trick if you don't want to render for such a long time is to have the glass be completely transparent to the light (maybe less realistic but will cut your rendering time)

[![enter image description here][5]][5]

Yet another option is to add an object that will light the scene but its invisible to the camera and reflections:


[![enter image description here][6]][6]


(to deal with noise read: https://blender.stackexchange.com/questions/4980/how-to-avoid-noisy-renders-in-cycles and blender guru's article on [how to reduce fireflies][7])


  [1]: https://i.sstatic.net/ScwB3.jpg
  [2]: https://i.sstatic.net/L1OTJ.png
  [3]: https://blender.stackexchange.com/questions/43248/make-the-flame-of-a-candle-more-yellow
  [4]: https://i.sstatic.net/lTOE2.jpg
  [5]: https://i.sstatic.net/3JLvp.png
  [6]: https://i.sstatic.net/OjYNl.png
  [7]: http://www.blenderguru.com/articles/7-ways-get-rid-fireflies/