If you want to create a new file under a particular folder. then you first need to create a folder(if the folder does not exist).
If you want to create a folder in this /var/www path you have to write the following code on the terminal
$ cd /var/www/yourfoldername
After written the above code the path will be shown on the terminal /var/www/yourfoldername$
You can create a file on this path with the help of this code
/var/www/yourfoldername$ touch filename.
For example:- /var/www/upload$ touch ex1.php