What kind of icon do you mean? If you mean the standard glyphicons from mendix, then you can set this up in the properties of the button (property in general → “Icon”).
Hope this helps!
Hi priyanka sawant,
Add widget select button-----> button properties--->general-->icon-->select image
If you would like to add your own custom icon, in that case, you go your module and right click and say add->ImageCollection
under that add a 64x64 png image, that you want to use as icon
In your button properties, chose images instead of icon and select the image that you uploaded