I need help on Remote Functions please? [I need help!]

So I have FE turned on and I need to access PlayerGui to get into an AdminPanel to find the "selected" player. How would I do this? I read the wiki and I don't really understand the wiki fully. I like someone helping me with their own words usually. I don't have a script because I don't really know where to start. I'm not requesting the script, I just wanna know how to use remote functions to do what I said.

More in-depth

So I have this admin panel in PlayerGui. I'll show a picture. https://gyazo.com/0dfa8aaf2287dee4a9fad9029f2e3418

You have to select the player to do said function to them. Because PlayerGui does not replicate to the server, I want to grab the selected player with a Remote Function and tell the server the selected player. I've never used a remote function, so how would I do this? The wiki didn't make much sense to me. So basically, use a remote function to get something from the player gui

To access PlayerGui you need to use a local script if filtering enabled is turned on a server sided script cannot access PlayerGui if filtering enabled is turned on.

Also if you wan't to access the PlayerGui heres how you do it (local script)

game.Players.LocalPlayer.PlayerGui:FindFirstChild(" ") -- Name of gui