cant send code to arduino uno r3 (elegoo)

Arduino: 1.8.9 (Linux), Board: "Arduino/Genuino Uno"

The sketch name had to be modified.
Sketch names must start with a letter or number, followed by letters,
numbers, dashes, dots and underscores. Maximum length is 63 characters.
Sketch uses 2232 bytes (6%) of program storage space. Maximum is 32256 bytes.
Global variables use 35 bytes (1%) of dynamic memory, leaving 2013 bytes for local variables. Maximum is 2048 bytes.
avrdude: ser_open(): can't open device "/dev/ttyACM0": Permission denied
Problem uploading to board. See for suggestions.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

thats the error message.
dont know if it helps but this is on ubuntu linux

Did you bother Googling the error message ?

See for suggestions.

So, why didn't you? Where, on the list of suggestions, is "Post in the wrong section of the forum, with NO details"?

i have done something in the terminal which may work (i don't really know ) but i know that its stupid what i am asking but im new to anything not entirely hardware related.

i have done something in the terminal which may work

Did it work, or didn't it?