If you wan't to set it programmatically you cold do something like this:

DynamicProperty primary = DynamicProperty.Load(pageId,"PropertyName");

primary.PropertyValue.Value = "yourvalue";

primary.Save();

Hi,

    Thanks for the reply. I am using CMS R2 SP1 and Enoteca as sample site. I want to change the Enoteca site logo i.e. I want to set a different image path in dynamic property named "LogoUrl" so that it can be shown in all the pages. Can you tell me where the values are initially set? is there any alternate way to change it from CmsCommerceManager?

I haven't worked with commerce but if you log in to edit mode and have "Admin" user rights you should be able to change the dynamic properties with via the dynamic property page that you can access via a tool button in the upper left corner.  Click on the start page before going in and changing the dynamic properties.