см. ResourceManager class
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Now suppose that a ResourceManager has been created to represent the resources with this basename. Using the ResourceManager, you can obtain a ResourceSet that encapsulates "MyResources.ja-JP.resources" by calling GetResourceSet(new CultureInfo ("ja-JP"), TRUE, FALSE). Or, if you know that "MyResources" contains a resource named "TOOLBAR_ICON", you can obtain the value of that resource localized for Japan by calling GetObject("TOOLBAR_ICON", new CultureInfo("ja-JP")).
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There's several methods to work with resouces in .NET Framework:

1. Create a .resource and add icons to the file, and then add the .resource file to your project and set the "Build Action" property to "Embedded Resource". Now, you
can use ResourceManager to retrieve the icons from the assembly.

There are some handy tools you can use to work with .resource and .resx files:

Resourcer for .NET
http://www.aisto.com/roeder/dotnet/

ResEditor in FrameworkSDK (Compile it before using)
FrameworkSDK\Samples\tutorials\resourcesandlocalization\reseditor\ResEditor.exe

2. You can also embed resources to the assembly directly using "Add Existing Item..." menu option. To retrieve these directly embedded resources, you can use
GetManifestResourceStream method to load the specified manifest resource from this assembly and cast the stream to appropriate type.