NOTE: .cshtml files are compiled by ASP.NET runtime, accepting ASP.NET-specific notations. In our case, we just use relative image path (~/...) which will be computed during compile time (more on this topic on MSDN).
Download the attached GSP.png logo and place it into "...\GeoMedia SmartClient\Program\Workflows\Custom\Images" folder.
Run the Workflow, you should see result similar to:
To study more on the customization approaches we recommend to visit the online documentation - Workflow Manager Developer Guide, topic Workflow Design > Views and Templates.
Also see attached sample FormHeader.zip with related .cshtml and image files.