Project references missing

I created a SitefinityWebApp and uploaded it on TFS, when getting the solution from another machine all of the references are missing and does not to compile since classes from them are used.

What am I doing wrong what shall I do when I want to be able to work from different workstations on the solution, please help.

I tried to add the solution the the project manager but its stays offline how can I bring it online?

Best regards.

Edit: Solution - > The bin folder containing dlls should be added to project and uploaded.