I'm also a beginner and I liked this recipe so much, I like smoothies because they are quite simple to make) Here's my favourie green smoothie recipe:
1 cup water
1 cup frozen mixed berries
1 cup kale
1/2 cup aloe vera juice - I don't use bottled juice but make natural one from the leaves, here's one of aloe vera juice recipe (last but one paragraph)
1/2 banana

Tear kale leaves off of stems and tear into small shapes. Put everything into a blender and blend until smooth.