See solution below.
Explanation:
Add a slot
1. In the Azure portal, search for and select App Services and select your app az400-11566895-main.

2. In the left pane, select Deployment slots > Add Slot.

3. In the Add a slot dialog box, give the slot a name, and select whether to clone an app configuration from another deployment slot. Select Add to continue.

4. After the slot is added, select Close to close the dialog box. The new slot is now shown on the Deployment slots page.

Reference:
https://docs.microsoft.com/en-us/azure/app-service/deploy-staging-slots

There are two different ways to deploy templates to Azure DevOps Services. Both methods provide the same results, so choosethe one that best fits your workflow.
1. Add a single step to your build pipeline that runs the PowerShell script that's included in the Azure Resource Group deployment project (Deploy-AzureResourceGroup.ps1). The script copies artifacts and then deploysthe template.
2. Add multiple Azure DevOps Services build steps, each one performing a stage task.
The first option has the advantage of using the same script used by developers in Visual Studio and providing consistency throughout the lifecycle.
s:
https://docs.microsoft.com/en-us/azure/vs-azure-tools-resource-groups-ci-in-vsts

Explanation:

To start monitoring all pipelines in a project, use the following command inside a channel:
@azure pipelines subscribe [project ur1]
The project URL can be to any page within your project (except URLs to pipelines).
For example:
@azure pipelines subscribe https://dev.azure.com/myorg/myproject/
Reference:
https://docs.microsoft.com/en-us/azure/devops/pipelines/integrations/microsoft-teams

Customizing Kanban boards
To maximize a team's ability to consistently deliver high quality software, Kanban emphasize two main practices. The first, visualize the flow of work, requires you to map your team's workflow stages and configure your Kanban board to match. Your Kanban board turns your backlog into an interactive signboard, providing a visual flow of work.
Reference:
https://azuredevopslabs.com/labs/azuredevops/agile/