Dims being used by .class File - class

Question

I have this and I want to use something similar to the way Java uses .class files to be able to call events and use them in my main code.
The problem is that I cannot get the .class file to use my Dims
Form1.vb:
Namespace LFS_External_Client
Public Class Form1
Inherits Form
Private OutGauge As OutGaugeInterface
Dim SpeedPref As String
Dim FuelCapacity As String
Dim Fuel As String
Public Sub New()
InitializeComponent()
End Sub
Private Sub Form1_Load() Handles MyBase.Load
Some Code
GetFuel()
End Sub
End Class
End Namespace
Then in the Dataproccer.vb (.class file):
Public Class DataProcesser
Public Sub GetFuel()
Some Code
Fuel = og.Fuel.ToString() * FuelCapacity
End Sub
End Class
Code was shortened but has all of the relevant and necessary parts.

Answer 1

If you want to use the actual variables from the form instead of passing them through the method calls, you would need to declare them public instead of using dim:
...
Private OutGauge As OutGaugeInterface
Public SpeedPref As String
Public FuelCapacity As String
Public Fuel As String
...

Answer 2

Dim FuelCapacity As String
Private Sub Form1_Load() Handles MyBase.Load
Some Code
DataProcesser.GetFuel(FuelCapacity)
End Sub
Public Shared Sub GetFuel(Byval FuelCapacity as string)
Some Code
Fuel = og.Fuel.ToString() * FuelCapacity
End Sub

Answer 3

Looking at the MSDN page for the Dim Statement.
It states:
Code outside a class, structure, or module must qualify a member
variable's name with the name of that class, structure, or module.
Code outside a procedure or block cannot refer to any local variables
within that procedure or block.
Also according to this MSDN article the default access level for the Dim Statement is Private at the Module Level.
So why not make GetFuel a function and pass the FuelCapacity in like #kcBeard states and return the Fuel value.
Private Sub Form1_Load() Handles MyBase.Load
Some Code
Fuel = DataProcesser.GetFuel(FuelCapacity)
End Sub
Public Shared Function GetFuel(Byval FuelCapacity as string) as string
Some Code
return og.Fuel.ToString() * FuelCapacity
End Function

Answer 4

You can make SpeedPref, FuelCapacity and Fuel public member variables, however a better approach would be to make them properties on the class with appropriate getters and setters. Dim just declares a variable. Please see the modified code sample below:
Form1.vb:
Namespace LFS_External_Client
Public Class Form1
Inherits Form
Private OutGauge As OutGaugeInterface
Private _SpeedPref As String
Private _FuelCapacity As String
Private _Fuel As String
Public Property SpeedPref
Get
return _SpeedPref
End Get
Set(value As String)
_SpeedPref = value
End Set
End Property
...
End Class
End Namespace