How do I use webhooks to send a message in Discord when a player touches a block?

local http = game:GetService("HttpService")
local Data = {
    ["content"] = "message"
}

Data = http:JSONEncode(Data)

http:PostAsync("webhook link", Data) 

This code only sends a message using webhook when a player joins a game, I want to make it send a message only on touch of a part.