Do you get the above message when trying to open an application? If so, you are seeing one of the security features of OSX. By default, your Mac is set to only allow recognised safe applications to open on your computer.
You can change this setting in the Security & Privacy section of the System Preferences. You can choose to allow apps downloaded from:
– The Mac App Store
– The Mac App Store and identified developers
The last option is the least secure, so only select this if you are confident the app you are using is genuine. Try to download software from the Mac App Store or directly from a developer’s own website.