今天花一點時間理解了怎麼進入admin後台
移動到主目錄，使用下列指令讓SQLite資料庫(預設是SQLite，依照自己的需求可以替換)
建立所有需要的初始化Table

python manage.py migrate

會跳出類似下列的輸出表示已經安裝了這四個app(admin, auth, contenttypes, sessions)

Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying auth.0012_alter_user_first_name_max_length... OK
  Applying sessions.0001_initial... OK

移動到主目錄，使用下列指令建立管理員

python manage.py createsuperuser

跳出以下設定帳號密碼的程序

Username (leave blank to use 'mark'): admin
Email address: mark@ittest.com
Password:
Password (again):
Superuser created successfully.

瀏覽器進入 http://127.0.0.1:8000/admin/
輸入你的admin帳密

之後會成功進入後台