No documentation on Material Icons

I am trying to use the menu builder for the first time and I would like to replace the icon. The icon tool offers a link to the material Icon site which is helpful, but there is zero documentation on how to add our choosen icon into uipress after we found one. I typed it’s icon name (‘ecg_heart’) back into the UIpress search bar and it doesn’t show up. How am I supposed to add the icon?