I use C# when writing Revit API code because that's what all the samples are written in, but I might be able to get you pointed in the right direction with some additional details. Are you looking to assign a value to a specific parameter? For example: Height=30"? If so you first have to "get" the parameter. In the example in spidernet he goes through every parameter of a selected element:
Dim element As Autodesk.Revit.DB.Element = SelElement(cmdData.Application.ActiveUIDocument.Selection).Element 'Prompts you to select an element
For Each p As Parameter In element.Parameters 'Goes through every parameter in "element" and assigns the parameter to "p"
If p.Definition.Name = "Height" Then 'Check if "p" is the name you want, "Height"
p.Set(2.5) 'Because Revit knows FEET, so in order to type in 30in you use 2.5
End If
Next 'Loop through parameters
If you're looking for it to do something else, please post again.
Also, not sure you're aware, but a blog that is FULL is great Revit API info is Jeremy Tammik's: http://thebuildingcoder.typepad.com. A lot of his examples are C#, which is why I started learning C# instead of VB.NET.
If you don't have it already, make sure you get the SDK for Revit 2014 here: http://images.autodesk.com/adsk/files/Revit2014SDK_RTM0.exe
It has a TON of samples that might help too. Good Luck!