Dim Friends(0 To 10) As String

Private Sub Command1_Click()
If Friends(any) = text1.text Then   '(what should I put here instead of any?)
MsgBox "You already have " &  text1.text " in the list 
else

end if
End Sub

Dim MyFriendCount As Integer, LoopCounter As Integer

MyFriendCount = -1

Dim FoundFriend As Boolean
If MyFriendCount = -1 Then 'no friend have been entered

ElseIf MyFriendCount > 10 Then 'too many friends or you need to redimension array so notify user...

Else 'need to check to see if you have already entered friend
  For LoopCounter = 0 To MyFriendCount
    If UCase(Text1.Text) = UCase(Friends(LoopCount)) Then
      FoundFriend = True
    Else
      FoundFriend = False
    End If
  Next LoopCount
 
  If FoundFriend = True Then
    'notify user
  Else
    MyFriendCount = MyFriendCount + 1
    Friends(MyFriendCount) = Text1.Text
  End If
End If