If you're just doing
Code:
Dim dsh as DictionarySectionHandler
then you either need to:
1) have an 'Imports System.Configuration' at the top of the code file.
2) have a project level import (from your project property pages, accessed by right clicking your project in Solution Explorer and choosing properties, go into 'Common Properties'->'Imports' and put in System.Configuration).
3) Reference the whole Namespace every time you need to (i.e. 'Dim dsh as System.Configuration.DictionarySectionHandler').