1.Install the SPO management shell
2.Save the following code to your machine as “EnableSideLoading.ps1”.

side loading Apps _ 17032016

side loading Apps _ 01_17032016

3.Execute EnableSideLoading.ps1 from PowerShell.
4.Provide the URL for the site collection where sideloading should be enabled.
5.Enter your user credentials. You must be a Tenant Admin to activate this feature.
6.Once the script has run successfully, you should be able to install apps from Visual Studio!