save time with the desired date

<MKB:TimeSelector ID="TimeFrom" runat="server" DisplaySeconds="False"></MKB:TimeSelector>

and a text box which is having a date.

VehicleBookingDate.Text

I want to save date and time in my database. for that if I want to do like below

 string t1 = tsTimeFrom.Hour.ToString() + ":" + tsTimeFrom.Minute.ToString() + " " + tsTimeFrom.AmPm.ToString();

 DateTime Time_From = Convert.ToDateTime(t1);

It saves time with current date, where as I want to save this time with this date which is in VehicleBookingDate.Text.

how can I do that.

Thanks