How to Turn Your Mac Into an FTP ServerIn Feburary 2016 13,

In Feburary 2016 13,
Click the blue Apple logo in the top left corner and select 'System Preferences.'
Select 'Sharing' in the 'Internet & Network' section of the 'System Preferences' window.
Check 'FTP Access' in the list of services. Your Home directory is the one that people will see when they connect to your FTP.
How to Set Up FTP Access Outside Your Home Network
Locate your external IP address and take note of it. You can find this by going to whatismyip.com on the Mac set up as an FTP server.
Locate your Mac's internal IP address and write it down. Go to 'System Preferences' > 'Sharing' and select (don't uncheck the check box) 'FTP Access.' The IP address will display below the Services box.
Map port 21 on your router to the internal IP address of your Mac. Most routers have a web-based admin screen that you can use to map the ports. Refer to your router's documentation.
How to Connect to Your FTP Server From Another Mac
Open the Finder.
Click 'Go' and select 'Connect to Server.'
Type in the external IP address you found in the previous section and click 'Connect.'
Enter in your user name and password. If you don't want to give out your Mac's (the one you set up as an FTP Server) user name and password, create a new account for FTP users by going to 'System Preferences' > 'Accounts.'
How to Connect to Your FTP Server From a Windows PC
Create a new Account for Windows users on the Mac Computer you've created the FTP server by going to 'System Preferences' > 'Accounts.'
Open Windows Explorer and type in the External IP address for your Mac's FTP server that you found using whatismyip.com. Hit the 'Return' key.
Click 'OK' on the error message that pops up.
Select 'FIle' > 'Login As...' in the menu of the Windows Explorer window.
Type in the username and password you set up in Step 1 of this section.
Click the 'Log On' button, and you should now see the folders and files of the FTP server.
In Feburary 2016 13,