Add colours to background post of user groups

[Saint Francis]

I'm really lost here, I've been searching the internet for ages and I know it's possible but I can't seem to find anyway to add a coloured background behind each post of a certain user group, so for example Moderator has a green background on post and Admin has a red background, how do I do that?

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How do I also add alerts to my forums? So if you post a thread and someone replies, you get an alert, I've seen it on another mybb forums, so I know it is possible.

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This is a bit of a silly and basic question but how do I add pages to the website?

I apologize for the mass of questions, new to this and would love to get this all set up.

Thanks in advance.

I believe if you search plug-ins , there might be one for that.