The Montage is not a sampler. And although you can load Waveforms made for the Motif XF, unlike the XF you do not have the same capability to create/edit/map individual samples for Waveforms.

A Waveform, in Yamaha-speak, is a collection of samples mapped horizontal to Key Ranges and vertically to Velocity Ranges (Keybanks). The difference between a .wav and a Waveform is the additional information that allows the audio to played as a musical sound (with pitch adjustment and dynamics). The Motif XF as a Sampler had the ability to convert .wav into Waveforms, as well as edit and loop the data.

You can certainly load .wav files to Montage, here's how:

You can go to the individual Element screen and load your audio file directly to an Element.
From HOME, press [CATEGORY SEARCH]
Touch "INIT"
Select "INIT Normal (AWM2)" > Enter

Press [EDIT]
Press [PART SELECT 1]
In the screen along the bottom touch Element "1"
Touch "OSC/Tune"
Touch the box "New Waveform"

This will open the Load "Audio file" window where you can start importing your data into a Waveform.
Each Waveform can have 256 Keybanks ( a KeyBank is the Note Range/Velocity Range) to add a new Key Bank to the current Waveform, you must touch the "Add KeyBank" box.

Please the Reference Manual pages 94-98 for more details.

Thank you, Bad Mister! So how can i load a wav file and set it to loop? 5I use this alot.

The sample, as I tried to explain, must be prepared elsewhere. You can only import "prepared" data into Montage. There is no facility in Montage to turn Loop on or off, the imported data must already be set to Loop.

In what format are your audio files?

Its sounds like we have to buy a John Melas Waveform Editor software and Map & Edit the sample that we want to play on the keyboard for Montage and export - Import back to Montage so that we can play it on the Montage like Montage Factory sounds