Portable means the program runs immediately and doesn't ask to be added in "Programs and Features" of Windows.
I only know in Visual Studio C# 2015 to press Build->Publish, and publish the program to a setup.exe file with a folder near, and when I run setup.exe it adds itself to Programs and Features...
The program is a Windows Forms Application program.
Change the build configuration to: Release
Build the solution.
Zip the files in the bin\Release folder.
Unzip on another PC.
Run the exe file.