Apache: How to adjust permissions for folder

Hey there

I am building a site with music and moviereviews using PHP and MySQL on an Apache server. Now I added a function that makes a .txt backup of each review added to the database. But this only works when I use it (the site is hosted on my own computer, using Apache as webserver) but when somebody else tries of the users on the site uses the backupfunction it won't work.

I think this has to do with the permissions of the folder that the backups are written to. I, who visits the site from localhost, has all the rights I need, but any one visiting the site from their computer doesn't.

Have I guessed right and if so, how do I set the right permissions for that folder?

If not, what else could be wrong? Is this a unsecure way of doing it?

Thankful for help!