After implementing Office Web Apps server in a SharePoint 2013 environment, the default behaviour for opening Office documents is to launch in the browser, not the client application. However, this might not be your preferred method, or perhaps you have different policies for different web applications. Changing the configuration is relatively straight forward but in the interest of keeping this post brief, check out this TechNet Article for full instructions.
Before you steam ahead though, be aware that the OpenInClient feature needs to be enabled in SharePoint first. Exposing the feature can be achieved quite quickly with a simple PowerShell cmdlet, for example:
Get-SPFeature –Identity 8A4B8DE2-6FD8-41e9-923C-C7C3C00F8295