I cannot start any port with Motoko

Question

I am trying to learn Motoko, i wrote following simply code;

import Debug "mo:base/Debug"

actor DBank {
  var currentValue = 300;
  let id = 12423532415345;
      Debug.print(debug_show(currentValue));


  public func topUp() {
    currentValue += 1;
    Debug.print(debug_show(currentValue));
  }
}

Then, I first, started it by dfx start, then I deployed by dfx deploy.

After that, I created the candid and I got the key with the command of dfx canister id __Candid_UI

But I cannot lunch the page with http://127.0.0.1:8000/?canisterId=

Can you please help me to resolve this?

I tried the instructions on the following page; https://internetcomputer.org/docs/current/developer-docs/backend/candid/candid-howto

and I got nothing. Thanks in advance.