start an UGC item update. Set changed properties before commiting update with CommitItemUpdate()
public static UGCUpdateHandle_t StartItemUpdate(AppId_t nConsumerAppId, PublishedFileId_t nPublishedFileID) { InteropHelp.TestIfAvailableClient(); return (UGCUpdateHandle_t)NativeMethods.ISteamUGC_StartItemUpdate(nConsumerAppId, nPublishedFileID); }