Linux "Serial Port" problem SOLVED!!! (Ubuntu)

Hey! I got my arduino a few hours ago and i couldn't upload any code to it because an error message came up all the time saying i need to select my serial port. Tools > Serial Port didn't show up. It was grey. After some time I started searching for online arduino programming because i was excited to program my arduino. I came up to a website, , and it saved me hours of trouble. First sign up and after you activate your account start following the instructions. I followed the instructions step by step (only took 5 min) and when i launched my Arduino IDE the serial port showed up. It work perfectly now.!!