Orientation: My goal here is to share my experiences in trying to learn more about Tibetan Buddhism. It assumes you are interested in Tibetan Buddhism and are alone in your search; no friends or family who are also Buddhists. Take my comments as they are, just comments; one person’s experience. And if it helps you on your way, I am very glad for that.
One confusing thing I found as I navigated the intricacies of Tibetan cosmology, was the existence of dozens of different deities. This pretty much flipped me out, because I thought that Tibetan Buddhism was ultimately atheistic; meaning there is no “god” per se. So, at first, I thought I was expected to be worshipping all of these “deities”.
But, as it turns out, while deities are used a lot in Tibetan Buddhism, they are not “gods” in the sense that we are used to in the West. So you can relax. No one is really worshiping anyone. But you will have to become familiar with the main ones, like Chenrezig, Red, Green and/or White Tara, and Vajrasattva for example. I am no expert. Nor am I qualified to say much more than this. But know that when you enter a shrine room, whether in a large shrine, or in a lama’s quarters, or in someone’s house, you will see images of many different deities. Get used to it. They are everywhere. They are integral. And they are what will make you successful on your path to liberation.
I will say that, on the Vajrayana Buddhist view (all Tibetans are Vajrayana pretty much), the deity is often talked about as a “wisdom being” and they are beings that play a large role in the visualizations than happen during many practices. In some ways they are “separate” from you, and in other ways, the “wisdom being” is none other than you, yourself. To fully understand this idea, you need a lama to teach you about it. I have just roughly tried to point you in a very general direction.
Depending on the lineage you find yourself in, and the lama you are working with, certain deities will take the lead over others. And each deity has corresponding practices and liturgies which are practiced. It takes time to sort out which deity is for what purpose, and what their characteristics are, and how they can help you. Be patient. Attend as many teachings as you can find offered by lamas of your lineage. They will be able to clarify many things for you.