【Class Library】

'============================================================
'SecondTime   0時0分0秒を基準に、それからの経過時間を秒で返す
'------引数--------------------------------------------------
'h,m,s   それぞれ時，分，秒
'============================================================
Public Function SecondTime(h As Long, m As Long, s As Long) _
                As Long
    SecondTime = h * 3600 + m * 60 + s
End Function

'============================================================
'GetTimer    時間ss(秒)から時間ms(秒)までの時間を、
'            h時間m分s秒の形で返す。（時間差の計算）
'------引数--------------------------------------------------
'ss,ms      時間差を計算したい時間(ss＜ms)
'h,m,s      時間差、それぞれ時，分，秒を格納する
'============================================================
Public Sub GetTimer(ss As Long, ms As Long, h As Long, _
                   m As Long, s As Long)
    h = (ms - ss) \ 3600&
    m = (ms - ss - h * 3600&) \ 60&
    s = (ms - ss - h * 3600&) Mod 60&
End Sub

    Dim ct As New CGetTime
    Dim h As Long, m As Long, s As Long
    Dim sec As Long
    'ある時刻を秒に換算
    sec = ct.SecondTime(ある時間, 分, 秒)
    '0時0分0秒からの時間差を求める＝求めたい時刻
    Call ct.GetTimer(0, sec + ？秒後, h, m, s)
    Label1.Caption = h & "時" & m & "分" & s & "秒です"