An error occurred during installation

hello ,

 an error occur during my installtation as below:

The directory “/var/www/” does not exist and could not be created.

 here is the link:

what should i do? thanks

you should give the write permission for proper user (e.g. www-data or nginx) to the directory /var/www/ or simply give access for all users: chmod 777 /var/www/

thank you so much , the problem is fixed.