You will first need to evaluate whether the glass is worth repairing. If there is significant damage, then it may be a better idea to call a professional repair company to see if they can help.
If you think the repair can be done by yourself, then invest in a glass repair kit, evaluare the situation and clean the flass before doing anything else. Follow the instructions in your repair kit and apply the correct amount of resin to your broken piece of glass. Make sure to also follow the instructions when it comes to applying the bridge to the glass. You will need to apply a reasonable amount of pressure.
Once you have complete your repair, you will find excess resin on the glass. Just clean this up with a razor blade.