Hello Deniz,
I was able to get Team project file to work as follows:
I am not sure which CCS version you are using but I tried this on CCS v5.5. I first opened Git Repository perspective, (Window -> Open Perspective->Other then select "Git repository exploring"). I then cloned a repository into my workspace directory. I selected to import all projects (beyond this first time, other team members would need to choose the option to not select any projects to be automatically imported). I then switched to CCS Edit perspective, where project explorer is now showing imported projects(with source control decorators). Next I created a .psf file by selecting Export->Team->Team Project Set. I selected projects that I wanted to belong to this set. I saved the psf file in my git repo, which I then committed.
Other team members would then clone a repo (do not automatically import projects) and select File->Import-> Team -> Team project file and navigate to .psf file.
Martin