public class VFController
{
    private final ApexPages.StandardController theController;
    public List<Opportunity> listOpps = new List<Opportunity>();
 
    public VFController(ApexPages.StandardController stdController)
    {
          theController = stdController;
    }
    // Code we will invoke on page load.
    public PageReference autoRun()
    {
        for (Opportunity opp:[select id, name from Opportunity where id =:theController.getId()])
            {
	        opp.Name = opp.name + ' test';
                listOpps.add(opp);
	    }
		Database.update(listOpps);
 
	return theController.view().setRedirect(true);
    }
}

<apex:page standardController="Opportunity"
extensions="VFController"
action="{!autoRun}"
>
<apex:sectionHeader title="Invoking Apex from a Button"/>
<apex:outputPanel>
You shoudn't see this page...
</apex:outputPanel>
</apex:page>

Dim arrUpdateID As New ArrayList  'This ArrayList holds the Opportunity IDs I need to update, I didn't included the query - that will be your task
 
Dim objOppx(199) As Opportunity
 
For d = d To arrUpdateID.Count - 1
 
Dim updateOppx As New Opportunity
 
updateOppx.Id = arrUpdateID(d) ' You need an ID when you update
updateOppx.Downloaded__c = True ' This is a checkbox in SFDC where I'm setting it to true
updateOppx.Downloaded__cSpecified = True ' This is required when updating a boolean field
objOppx(d) = updateOppx ' Storing opportunity values to  objOppx which is an array of Oppty
 
Next
 
Dim sr() As SaveResult = sfdc.update(objOppx) ' This is where the updating happens, this line of code should be outside the loop
 
For j As Integer = 0 To sr.Length - 1
Dim msgerr As String
 
If Not sr(j).success Then
msgerr = "Error updating Opportunity ID: " + sr(j).id + ". The error was: " _
+ sr(j).errors(0).message
End If
 
Next