Automatically mount ftp folder - WiFi connection

Hi all… I am pretty new on this wonderful raspberry world and I need your help.
I have a Raspberry PI 2 and I tried automonting ftp folder at boot…

following this and other links I managed to mount ftp folder, but every time I try modifying /etc/fstab OS starts in emergency mode.
Do you know how to help me… I also could mount the same folder using samba… please consider that my connection is done using wifi

Thanks for your support