Step 1:
Click on the [+] ICON on the left of your screen and scroll down to EFFECTS.
Depending on the product you are showcasing, your choice of effects/texture may vary. Click on the effect/texture to add it to the canvas.
Step 2:
You can make changes to the appearance of the effect using the EDITS PANEL on the right.
Step 3:
You can double-click on the effect to crop parts of it and scatter it around your image.