<SharePointPermissionAttribute(SecurityAction.LinkDemand, ObjectModel:=True)> _
<SharePointPermissionAttribute(SecurityAction.InheritanceDemand, ObjectModel:=True)> _
Public Class SPFile

Dim instance As SPFile

[SharePointPermissionAttribute(SecurityAction.LinkDemand, ObjectModel=true)] 
[SharePointPermissionAttribute(SecurityAction.InheritanceDemand, ObjectModel=true)] 
public class SPFile

Dim siteCollection As SPSite = SPContext.Current.Site
Dim srcSite As SPWeb = siteCollection.AllWebs("Source_Site_Name")
Dim destSites As SPWebCollection = 
    siteCollection.AllWebs("Destination_Site_Name").Webs

Dim srcFile As SPFile = 
    srcSite.GetFile("Source_Folder_Name/Source_File")
Dim fileName As String = srcFile.Name
Dim binFile As Byte() = srcFile.OpenBinary()

Dim destSite As SPWeb

For Each destSite In  destSites

    If destSite.GetFolder("Shared Documents").Exists Then

        Dim destFolder As SPFolder = 
            destSite.GetFolder("Shared Documents")

        destFolder.Files.Add(fileName, binFile, True)

    End If

Next destSite

SPSite oSiteCollection = SPContext.Current.Site;
SPWeb oWebsiteSrc = oSiteCollection.AllWebs["Source_Site_Name"];
SPWebCollection collWebsites = 
    oSiteCollection.AllWebs["Destination_Site_Name"].Webs;

SPFile oFile = oWebsiteSrc.GetFile("Source_Folder_Name/Source_File");
string strFilename = oFile.Name;
byte[] binFile = oFile.OpenBinary();

foreach (SPWeb oWebsite in collWebsites)
{
    if (oWebsite.GetFolder("Shared Documents").Exists)
    {
        SPFolder oFolder = oWebsite.GetFolder("Shared Documents");
        oFolder.Files.Add(strFilename, binFile, true);
    }
    oWebsite.Dispose(); 
}
oWebsiteSrc.Dispose();