You can add a Reference by Right Click on the References folder or Project node then click on Add Reference. In the .NET section, Aspose.Pdf dlls are available in the .NET section of popup window as shown in the attached screenshot. After adding the reference hopefully you can use Aspose.Pdf for .NET.
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thanks the screen shot was useful, eventually I found it: The reference pointed to the latest 4.0 version, this one doesn't work, whereas the 2.0 is ok, I forgot that the web app is compiled with VS2008 not VS2010.
I am glad to hear that the problem is fixed. Please continue evaluating our products and in case you encounter any issue or you have any further query, please feel free to contact.
You may consider checking our various useful resource over following links
Aspose.Pdf for .NET Demos = http://www.aspose.com/demos/.net-components/aspose.pdf/default.aspx
Aspose.Pdf for .NET Video Tutorials = http://www.aspose.com/videos/aspose.pdf/aspose.pdf-for-.net/default.aspx