Getting images from a ftp. How?

I need help please. I am working with a friend making an app. We are both not that clever with android
What we are trying to do..
We have 3 locations location1 ID1 location 2 ID2 location3 ID3.
I have an external ftp which had lots of images on 20 png files for each ID. they are updated every 6mins and the oldest is deleted.
The files are called ID.datetime.png .
So what im trying to do is when picked the location name it then goes to the ftp and gets the newest 6 png files for that station id.
Can someone tell me how to do this or share some code, thanks
PS the ftp is annon/annon too
thanks again