Can't edit files in '/var/www/' - Already followed a lot of tutorials

I'm trying to edit a PHP open source project, and I put it in /var/www to view the updates in real time using localhost. It works, but when I try to update one file of the project in Sublime Text I receive the following error:

Unable to save /var/www/howtoelementaryos/global.php Error: unable to create tmp file in /var/www/howtoelementaryos 

I want know what I can do to solve this problem, because I already followed these tutorials:

1. https://superuser.com/questions/378412/editing-files-in-var-www
2. Git unable to create file permission denied
3. https://askubuntu.com/questions/348427/cant-save-files-in-var-www-using-lamp-installed-with-tasksel
4. fatal: Unable to create temporary file '/home/username/git/myrepo.git/./objects/pack/tmp_pack_XXXXXX': Permission denied

And none of these helped me. Summarizing, what I can do to solve this issue?

Edit:

stat /var/www:

 File: `/var/www' Size: 4096 Blocks: 8 IO Block: 4096 directory Device: 806h/2054d Inode: 4202729 Links: 4 Access: (0777/drwxrwxrwx) Uid: ( 33/www-data) Gid: ( 33/www-data) Access: 2013-10-28 10:33:02.827949771 -0200 Modify: 2013-10-28 10:14:39.030751552 -0200 Change: 2013-10-28 10:33:02.827949771 -0200 Birth: - 

stat /var/www/howtoelementaryos:

 File: `/var/www/howtoelementaryos' Size: 4096 Blocks: 8 IO Block: 4096 directory Device: 806h/2054d Inode: 4195910 Links: 4 Access: (0775/drwxrwxr-x) Uid: ( 33/www-data) Gid: ( 33/www-data) Access: 2013-10-28 10:33:35.244209685 -0200 Modify: 2013-10-28 10:09:49.724196121 -0200 Change: 2013-10-28 10:33:02.831949803 -0200 Birth: -