As you're using .NET 2.0 you have to use the JSON libary by James, with download at Codeplex (version for .NET 2.0).
An example of using Json.NET
Add a reference to Newtonsoft.Json, and an Import Newtonsoft.Json in your class.
Example:
Import Newtonsoft.Json
Dim product As New Product()
product.Name = "Captopril"
product.Expiry = New DateTime(2008, 12, 28)
product.Price = 3.99D
product.Sizes = New String() {"Small", "Medium", "Large"}
'Call SeralizeObject to convert the object to JSON string'
Dim output As String = JavaScriptConvert.SerializeObject(product)
The output variable will hold the value:
{
"Name": "Captopril",
"Expiry": "\/Date(1230375600000+1300)\/",
"Price": 3.99,
"Sizes": [
"Small",
"Medium",
"Large"
]
}