This is a piece from my Final fantasy 11 Configurator that I made back when I used to play the game.

Start off with the imports:
Imports Microsoft.Win32
We'll now make a registrykey variable
  Dim FF_key As RegistryKey
Now we will make sure the location want it stored in that variable

 FF_key = Registry.LocalMachine.OpenSubKey("\Software\Microsoft\", True)
Basically what that is doing is it's going to look like the tree in the regeditor:

Granted I no longer have the game installed, I'm sure you will still get the point.

Now to read in the Keys that are already saved by the game. In this part I called a few keys that I wanted information from, so in order to do that I first declare my variables:

        Dim key_windowed_mode As String
        Dim key_res_1 As String
        Dim key_res_2 As String
        Dim key_3D_res_1 As String
        Dim key_3D_res_2 As String
        Dim key_texture_compress As String
        Dim key_on_screen_map As String

  key_res_1 = FF_key.GetValue("0001")
            key_res_2 = FF_key.GetValue("0002")
            key_3D_res_1 = FF_key.GetValue("0003")
            key_3D_res_2 = FF_key.GetValue("0004")
            key_texture_compress = FF_key.GetValue("0018")
            key_on_screen_map = FF_key.GetValue("0019")
The ("numbers") is the key name which holds the information that I wanted.

Now when it comes to writing it's just as easy:

 FF_key.SetValue("0034", 1, RegistryValueKind.DWord
Valuekind.dword is just the datatype, you don't always needs to do this but for this to work for me in this case I had to.