Hi, I'm Nathan.Sorry to hear that you're having trouble with this but I'll do my best to help you.
For the roku it does need power and hdmi,
you then take the Samsung tv remote, and press the INPUT (source) button on it, repeatedly, to cycle through the different input modes until you get to whichever port you connected the roku to (hdmi1, hdmi2, etc).
From there you should see the roku logo or home page, and you'll use the roku remote at that point.
It will guide you through the initial process of connecting to your home wifi network and then registering to a roku account, and from there you can start using apps like netflix.
Let me know if you get stuck.
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