"sudo" is basically to run a command as if you were the root . you can read it as "SuperUserDo".
So whenever you come across the problems like permission denied during any operation, just prefix "sudo" behind the command so that you get the rights to do everything you want.

I posted the commands above.

Ok, so I performed the command successfully and entered my password:

sudo chmod 775 /opt

But still I cannot copy (tried drag-n-drop) that extracted lampp folder to /opt !??! Ah mean, why is this sooooo difficult to do after using sudo?

How can I move or copy this lampp folder over to /opt via cli?

I even tried this command I found online to no avail: sudo tar xampp-linux-1.7.3a.tar.gz -C /opt

I'm at such an impasse.

Ok, so you changed the permissions on the directory, but did you change the group?

Originally you had the following for ls -ls /opt:
And with the above chmod you should now have (I would advise to check this is so):
But all this has done is allow the group 'root' to now also have write access to this directory.
As you are not in this group then you do not have access unless again using the sudo command.

However, if you were to issue:
This will then allow all users in the admin group to write to this directory.
(Chose admin as you previously indicated you are in this group)

The basic thing is for a user except root don't have write permissions to folders except your home (~/) folder. If you want write to other folders, use
sudo "commandName"
Changing permissions in the /opt is highly NOT recommended.
Further, you can change to root user by typing following in the terminal.
Then, you have write access to all the folders under /.

For your problem, use,
You forget the option -xf. -x option says to eXtract the given file.

HTH

Post the output which you did originally so we can now see the results.

Well. Still no go. This is the error messages now:

supra@supra-desktop:~$ ls
- Desktop Documents Downloads groups is ls Music Pictures Public Templates Videos

supra@supra-desktop:~$ sudo tar -xf xampp-linux-1.7.3a.tar.gz -C /opt
tar: xampp-linux-1.7.3a.tar.gz: Cannot open: No such file or directory
tar: Error is not recoverable: exiting now

The file is not at the location you think it is.
Where did you downloaded the file?
Desktop, Downloads....
First cd to the directory containing the tar archive.

Well, the 'Desktop Folder' shows the following folder:

- xampp-linux-1.7.3a.tar
- lampp (folder)

Also, looking at File Manager (Dolphin) it shows the same files in Documents (folder) and Desktop

supra@supra-desktop:~$ ls
- Desktop Documents Downloads groups is ls Music Pictures Public Templates Videos
supra@supra-desktop:~$ ls documents
ls: cannot access documents: No such file or directory
supra@supra-desktop:~$ ls /documents
ls: cannot access /documents: No such file or directory

Documents begins with a capital 'D'. Case sensitivity is important.

Do
cd to the directory created by th tar command
read the readme files

I think there is no need to change the permissions of /opt. What you all have to do is to run the xampp related executable file from command prompt as

If running from GUI, then:

then run the executable file from GUI mode..


Please correct me if wrong.