Command line builds:
devenv solutionfile.sln /build solutionconfig [ /project projectnameorfile [ /p
rojectconfig name ] ]

I try to build.........please could somebody tell me what is solutionconfig?

Release or Debug or any other custom configuration you have setup. By default you get the Release or Debug Configuration. This is needed only if you use the /project switch. If you use only the /solution switch, you can just give the solution file and the solutionconfig name and all the projects will be built. reference