Run following Commands to Run VBoxLinuxAdditions.
Note :- Guest Addition is used to Add-on Extra Features to your Virtual Machine.
1} Change Directory to Desktop.
cd Desktop
2} List all the items present on Desktop.
ls
3} After Doing ls you will see VBoxLinuxAddition.run. Give all the Permission to it using following command.
chmod -x VBoxLinuxAdditions.run
4} Run VBoxLinuxAddition.run.
./VBoxLinuxAdditions.run
5} Reboot your Virtual Machine/System.
reboot
Note :- If you are unable to find it on Desktop then Search it on the Optical Drive/Storage Media. You may find it on your Storage Media.
If Still have any problems running Guest Addition or to make Linux Full Screen.Mention your Errors in Comment Section.
Thank You,
Chandan Rajpurohit.