LED Panel: Need help making sense of this circuit

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First of all, I’m not sure if this is the right forum, if not, please feel free to five me a link to a community that can help me with that.

I am building lights for growing plants, and in order to keep the lamp small, I bought this:

l6EreAo.jpg800×800 103 KB
http://i.imgur.com/l6EreAo.jpg?1

Panel Size: 80x80

And thought I was smart enough to figure it out after I got them. Well… bad idea.

Here are the concrete questions:

Are the “ZD” slots meant for SMD Zener Diodes? (this is the only component I found that would match “ZD”)?

If yes, can you give me a few hints for choosing the right type?

Thank you for your help, and cheers.