First, call the police
Before you do anything else, you need to call the police. If you notice that your house has been broken into before you walk in, don't go inside. Call the police and wait for them to show up. By walking in you can be destroying evidence that could help the police find the robber, or worse, you could be risking walking in when the robber is still inside. If you saw the person, remember what they looked like (their sex, age, race, clothing, and where they went) so that you can tell the police. If you were inside your house when you realized you were robbed, try not to touch anything. Take pictures to show police and the insurance company. Most importantly remember to stay calm.
File a report
After the police come, they will most likely tell you about different ways you can get your report. This can include anything from filing a report online to going down to the police station. You will need to get your police report before you even try to file with your insurance company. Once you have the police report, you should immediately call your insurance company and fill them in on everything. At this point, they will want the information from the police report and will send a claims adjuster out to your home. This is where you will need to have your information to prove your stolen items. If you can find them, have receipts for your big ticket items and any other evidence you can find proving that your items were stolen. If you planned ahead, or if you're planning ahead for next time, have pictures of your room before the incident to show the insurance company in place of receipts.
Secure your home
Now that you've filed all of your reports, it is time to start putting your life back together, literally. Close up the point of entry. If it is a broken window, either replace it or board it up. Reinforce the weak parts of your entry points and consider putting in security cameras. Inform your neighbors about the robbery (if they haven't already noticed from the police officers at your house). Although the robber might not hit one of their houses, it's nice to have the extra eyes watching out.
Rest your mind
There is no amount of cameras or locks that are going to put your mind at ease. Your area of safety and solitude has just been ruined and that's something you can't change. It is alright to be upset. It is alright to be emotional. Consider taking a personal day from work to allow yourself to relax. It may be a while before you feel perfectly safe again, but give yourself a chance to come to terms with the robbery so you can move past it.