Finding a Textbox control on a page and setting it's value

 I'm fairly new to asp.net and the vb language, so what I am trying to do may seem a bit convoluted.
How can I find a control on a page based on it's name, and set a property of that control (.text for a textbox and .selected for a checkbox)?
I have a hashtable, and the value of each entry is made up of "destinationFieldName;destinationFieldType" so I can differentiate between textboxes and checkboxes with a case select.
 
Here's what I have in my page load:
 
1 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
2
3 Dim redirectFlag As Boolean = True
4 ...