Accessing Certain Functions In Class

I am currently trying to write classes so that I can access certain functions from any form within my VB project.

My class is defined thus:-
Public Class testclass
Public Function showmes()
MsgBox("Hello everyone"")
Return 0
End Function
End Class

I have added the class into my form using this at the top in the form:
Imports WindowsApplication1.testclass
Obviously, WindowsApplication1 being the name of my project, testclass being within a VB file, saved with my project.

I have attempted to call the function from the form using this:
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
showmes()
End Sub

However I am getting the error "Reference to a non-shared member requires an object reference." I don't understand why there is a problem, since I have used imports to reference the class.