The Ajax Control Toolkit contains a rich set of controls that you can use to build highly responsive and interactive Ajax-enabled ASP.NET Web Forms applications. Follow the steps below to download and start using the Ajax Control Toolkit with Visual Studio:
1- Download the Ajax Control Kit
The first step is to download the Ajax Control Toolkit. You can download the latest version of the Ajax Control Toolkit from CodePlex.
Click the Downloads tab at the CodePlex site to see the list of available Ajax Control Toolkit downloads. If you are using Visual Studio 2008 then you should pick the version of the Ajax Control Toolkit for .NET 3.5. If you are using Visual Studio 2010 then you can use either the .NET 4 or .NET 3.5 versions of the Ajax Control Toolkit.
Download the Binary version and not the Source version of the Ajax Control Toolkit. You should download the Source version of the Ajax Control Toolkit only when you are interested in extending the Ajax Control Toolkit.
2- Extract the Download
After downloading the Ajax Control Toolkit, you need to unblock and extract the files. Right-click the compressed file and click the Unblock button.
Next, right-click the compressed file and select the Extract All menu option.
3- Add the Ajax Control Toolkit to the Visual Studio Toolbox
The next step is to add the Ajax Control Toolkit to the Visual Studio Toolbox. Follow these steps:
a) Launch Visual Studio and create a new ASP.NET Web Forms project or website. Open Default.aspx in the Visual Studio editor.
b) Create a new Toolbox tab by right-clicking the Toolbox and selecting Add Tab. Name the new tab Ajax Control Toolkit.
c) Right-click beneath the new tab and select the menu option Choose Items… Click the Browse button and browse to the folder where you extracted the Ajax Control Toolkit. Pick the AjaxControlToolkit.dll and click the OK button to close the Choose Toolbox Items dialog.