Help with adding +1 to a textbox that starts at 1?

Modifying @Andromedual's answer using @xInfinityBear's comment and my modifications

The title above says it all, except for my modifications. What are my modifications? Well first off, he didn't clarify on where should this script be placed. Secondly, he used the unknown variables blahablahla and otherblaglahalhla, which might confuse the OP.

Example & How To Do It

Let's say you have a ScreenGui in StarterGui. Inside it, there is one TextBox and two TextButtons named Up and Down. Inside the ScreenGui, create a new LocalScript. Inside the script should look like this:

local gui = script.Parent -- StarterGui.ScreenGui
local textBox = gui:WaitForChild("TextBox")
local up = gui:WaitForChild("Up")
local down = gui:WaitForChild("Down")

local value = textBox:GetAttribute("Value") -- gets the attribute
if not value then -- if attribute wasn't created yet (nil)
    textBox:SetAttribute("Value", 0) -- creates a new attribute
    value = textBox:GetAttribute("Value")
end
textBox.Text = tostring(value) -- converts numbers to text

up.MouseButton1Down:Connect(function()
    local currentValue = textBox:GetAttribute("Value")
    textBox:SetAttribute("Value", (currentValue + 1)) -- adds 1 to the attribute
end)

down.MouseButton1Down:Connect(function()
    local currentValue = textBox:GetAttribute("Value")
    if currentValue > 0 then
        textBox:SetAttribute("Value", (currentValue + 1)) -- subtracts 1 from the attribute
    end
end)

textBox:GetAttributeChangedSignal("Value"):Connect(function() -- when the attribute changes
    local currentValue = textBox:GetAttribute("Value")
    textBox.Text = tostring(currentValue)
    textBox:SetAttribute("Value", math.clamp(currentValue, 0, math.huge)) --  if currentValue is less than 0 (min) it will change the attribute to 0
end)

WARNING: DO NOT COPY-PASTE THIS DIRECTLY TO YOUR CODE AS IT MIGHT NOT FUNCTION INTENDEDLY. THIS SOLUTION JUST GIVES YOU AN IDEA OF WHAT TO DO. IMPLEMENT THIS YOURSELF.

From what I understand, you want to make a textbox that will change from 1, 2, 3, or downwards like 3, 2, and 1 from what you press. I believe a good solution to do this would to create a local value inside your script, and make it +1 or -1 based on the button you press, like this?

local value = 0
blahablahla.Activated:Connect(function()
    value += 1
end)

otherblaglahalhla.Activated:Connect(function()
    if value > 0 then
        value -= 1
    end
end)

value.Changed:Connect(function()
    blahblahtextlabel.Text = value
end)

I haven't tested this but it should work. if it doesn't work experiment with it for a bit. if you need to add other things inside the text label, try

blahblahtextlabel.Text = ("Buying: " .. value)