Azure DevOps YAML self hosted agent pipeline build is stuck at locating self-agent

Question

Action: I tried to configure and run a simple c++ azure pipeline on a self-hosted Windows computer. I'm pretty new to all this. I ran the script below.

Expected: to see build task, display task, and clean task. to see the hello world.

Result: Error, the script can't find my build agent.

##[warning]An image label with the label Weltgeist does not exist.
,##[error]The remote provider was unable to process the request.
Pool: Azure Pipelines
Image: Weltgeist
Started: Today at 10:16 p.m.
Duration: 14m 23s

Info & Test:

1. My self-hosted agent name is Weltgeist and it's part of the default agent pools.it's a windows computer, with all g++, mingw and other related tools on it.

2. I tried my build task locally with no problem.

3. I tried my build task using azure 'ubuntu-latest' agent with no problem.

4. I created the self-hosted agent following these specification. I'm the owner of the azure repo. https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/v2-windows?view=azure-devops

How do I configure correctly the pool ymal parameter for self-hosted agent ? Do i have addition steps to do server side? or on azure repo configs? Any other idea of what went wrong?

# Starter pipeline
# Start with a minimal pipeline that you can customize to build and deploy your code.
# Add steps that build, run tests, deploy, and more:
# https://aka.ms/yaml

trigger:
- master

pool:
  vmImage: 'Weltgeist' #Testing with self-hosted agent

steps:
- script: |
    mkdir ./build
    g++ -g ./src/hello-world.cpp -o ./build/hello-world.exe
  displayName: 'Run a build script'

- script: |
    ./build/hello-world.exe
  displayName: 'Run Display task'

- script: |
    rm -r build
  displayName: 'Clean task'