Struggling to insert fire into a brick in a script?

Well depends if you want the player to join and then have the fire on their head or not. If you want the fire to be on player's head on join then put this normal script in Workspace or in ServerScriptService. In this case, we would use PlayerAdded

game.Players.PlayerAdded:connect(function(p)
    wait()
    local H = p:FindFirstChild("Character").Head --I'm not sure if this is how u get character beacuse I never done it before. If not please change.
    local newbaby = Instance.new("Fire")
    newbaby.Parent = H
end)

This will create a fire on join and makes it so that the fire is on the head of the player (character).

If this helped please upvote and accept the answer, I'm not sure if that's how you get the character though, but you get the idea.