How to get connected to a site in sharepoint.

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How to get connected to a site in sharepoint.
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1)
     Dim oWebsite As SPWeb = SPContext.Current.Web
2)
     Using oWebsiteRoot As SPWeb = SPContext.Current.Site.RootWeb
                ...
     End Using
3)
     Using oWebsite As SPWeb = SPContext.Current.Site.OpenWeb("Website_URL")
  ...
      End Using
4)
      Using oSiteCollection As New SPSite("http://server_name/")
         Using oWebsite As SPWeb = oSiteCollection.OpenWeb("Website_URL")
             Using oWebsiteRoot As SPWeb = oSiteCollection.RootWeb
                  ...
             End Using
         End Using
      End Using
5)
      Dim myWeb As SPWeb = SPContext.Current.Web
      Debug.WriteLine("MyWeb lists : ")
                        For Each aList As SPList In myWeb.Lists
                              Debug.WriteLine("************************************")
                              Debug.WriteLine("list Title (Display Name): " & aList)
                              Debug.WriteLine("list Title (Display Name): " + aList.Title)
                              Debug.WriteLine("list Root Folder Name: " + aList.RootFolder.Name)
                              Debug.WriteLine("************************************")
                         Next