How to install and use PoE loot filters

It's very simple to install Path of Exile loot filters:

Download desired filter at FilterBlast or at selected filter's official forum thread
(the file must have ".filter" extension)
In the game open Options, then open UI tab
Scroll down to the end and click Show Folder - this will open folder at location with path like "Documents/My Games/Path of Exile/"
Move or copy downloaded filter file into that folder
Switch back to the in-game Options screen and click Reload - this will update dropdown "List of Item Filters"
Select the filter from the list - "Item Filter loaded successfully" notification shall appear in the game's chat
Save options and enjoy the gameplay with selected loot filter!