How do I make it so when a certain username is inputted their image will appear on a part?

I'm trying to make the fallen screen from the hunger games, but I really can't do it. Everything I did looks wrong and I just don't know what to do at this point. (Btw I am using a surface-GUI)

Confirm button:

local b = script.Parent
local player = game.Players.LocalPlayer
local fallen = workspace.FallenScreen
local enabled = false

if b.Text == 'player'
    and
    enabled == true

Input box:

local b = script.Parent
local player = game.Players.LocalPlayer
local fallen = workspace.FallenScreen
local enabled = false

if b.Text == 'player'
    and
    enabled == true
    then
    workspace.FallenScreen.Decal.Texture = "I don't know how to get the player's picture either ):"

Has a bool value called "Enabled"

Thanks if you can help me, and I'm a bit of a noob and I think it's pretty obvious from this, so go easy on me, please! :)