Load image from share resource

Hi all.
I having development a small project by Xamarin-forms and encounter a problem.
I have a custom Listview that display images from my resource.
Problem here are i don't know how to organize resource to run well on both IOS and Android, and how to get Image Resource from "resource above". Like "Assets", "drawable" in android or "Resource" in IOS.
How to resolve this problem?
Sorry if my English is not good.
Thank all.