SPAttachmentCollection Class(Sharepoint List attachments)

PSite oSiteCollection = SPContext.Current.Site;
SPWebCollection collWebsites = oSiteCollection.AllWebs;

SPWeb oWebsite = collWebsites["Site_Name"];
SPFolder oFolder = oWebsite.Folders["Shared Documents"];

foreach (SPWeb oWebsiteNext in collWebsites)
{
    SPList oList = oWebsiteNext.Lists["List_Name"];
    SPListItem oListItem = oList.Items[0];
    SPAttachmentCollection collAttachments = oListItem.Attachments;

    SPFileCollection collFiles = oFolder.Files;

    foreach (SPFile oFile in collFiles)
    {
        string strFileName = oFile.Name;

        byte[] binFile = oFile.OpenBinary();

        collFiles.Add(strFileName, binFile);
    }

    oListItem.Update();
    oWebsiteNext.Dispose();
}
oWebsite.Dispose();