If all you want is a frame with a border, and not have to worry about Libs, this should create a simple 200x100 frame for you to work with
Lua Code:
local frame = CreateFrame("Frame", nil, UIParent)
frame:SetSize(200, 100)
frame:SetPoint("CENTER")
frame:SetBackdrop({
bgFile="Interface\\Tooltips\\UI-Tooltip-Background",
edgeFile="Interface\\Tooltips\\UI-Tooltip-Border",
tile=false,
tileSize=0,
edgeSize=2,})
frame:SetBackdropColor(0,0,0,0.5)
frame:SetBackdropBorderColor(0,0,0,1)