How to change Flutter for web Font?

I am trying to change the font of the title in my Flutter for Web Application how can i do it? I found out that the pubsec.yaml is completely different than the mobile version here is the file:

name: projectbaseclient
description: An app built using Flutter for web

environment:
  # You must be using Flutter >=1.5.0 or Dart >=2.3.0
  sdk: '>=2.3.0 <3.0.0'

dependencies:
  flutter_web: any
  flutter_web_ui: any

dev_dependencies:
  build_runner: ^1.5.0
  build_web_compilers: ^2.1.0
  pedantic: ^1.7.0

dependency_overrides:
  flutter_web:
    git:
      url: https://github.com/flutter/flutter_web
      path: packages/flutter_web
  flutter_web_ui:
    git:
      url: https://github.com/flutter/flutter_web
      path: packages/flutter_web_ui

I have already created a folder assets/fonts and added the fonts in the folder also i created the FontManifest.json and put it in the assets folder but it the code is not working it gives me error when i change the fontFamily parameter in the Text object.

how can i use the fonts to the Flutter for Web project?