Specifically if you can't find a fitting sound file for the integration in your track, you can ask here if someone else can find one. The same goes for images and signs.
Please specify exactly what you require so make sure to have a proper description.
One example for a sound description: cracking noises, rocks falling, under 30sec.
A sign description: 512x256 dimension, moving waterfall (animated) on the full sign
Just a little more elaborate maybe
