Where to download android for galaxy S5 (G900FZHU1ANE3)?
The newest available Image ( Android 5.0 ) for your Sm-G900F Samsung Galaxy s5 is available on sammobile. 

Look at the instructions for flashing on this site:

Extract (unzip) the firmware file
Download Odin v3.10.7
Extract Odin ZIP file
Open Odin v3.10.7
Reboot Phone in Download Mode (press and hold Home + Power + Volume Down buttons)
Connect phone and wait until you get a blue sign in Odin
Add the firmware file to AP / PDA
Make sure re-partition is NOT ticked
Click the start button, sit back and wait few minutes