In SharpDX.Toolkit content is loaded from a folder relative to the folder where your program is located. Also you should mark the texture with build action ToolkitTexture
(open file properties in Visual Studio).
After build, the file should be copied to a path like this:
H:\Programmieren\Pong\Pong\bin\Debug\Content\Ball.tkb`
(the extension may be different - I don't remember exactly).
After this, you can load the asset by calling ballTexture = Content.Load(@"Content\Ball");
Alternatively, you can set the root path for content manager during initialization:
Content.RootDirectory = "Content";
...
//and load the textures with
ballTexture = Content.Load(@"Ball");
All this is demonstrated in SharpDX Toolkit samples (located in Samples\SharpDXToolkitSamples.sln
).