[Virtualbox Guest Additions] "Please install the build and header files headers? - Debian

Install the following on your Ubuntu Guest :

sudo aptitude install build-essential linux-headers-`uname -r`

The re-try the Additions, you should be fine :)

Install Guest Additions on Linux guest

Again, a fairly simple procedure. Repeat the first step. This will mount the VirtualBox Guest Additions ISO (included with the program) as a CD-ROM drive inside the virtual machine.
A file manager windows might popup, depending on your guest configuration, showing all the available options, including Guest Additions for both 32-bit and 64-bit systems, Windows and Linux alike - and even Solaris, not surprising, considering VirtualBox owned by Sun. On most modern Linux distros, the system will auto-mount CD-ROMs and launch file browsers / managers.

Choose the right package for your hardware architecture. In our case, this is x86. Open a terminal window and run the script with root privileges:

sudo sh ./

See image:

Wait a few moments until the installation is complete. Reboot.

And that's it!