step1) place one fileUpload control from tool box
step2) in it's Button click event
    If FileUpload1.PostedFile Is Nothing  Then
                Response.Write("no file posted")
                
            Else
               Here Convert that image as byte and pass it
to function.
                Dim con As SqlConnection
                Dim cmd As SqlCommand
                Dim ds As New DataSet

                con = New
SqlConnection(ConfigurationManager.AppSettings("connectionString"))
                cmd = New SqlCommand("insert into tablename
values(@image_in), con)
 Dim imageByte(FileUpload1.PostedFile.InputStream.Length) As
Byte
               
FileUpload1.PostedFile.InputStream.Read(imageByte, 0,
imageByte.Length)
                cmd.Parameters.AddWithValue("@image_in",
imageByte)
                con.Open()
                cmd.ExecuteNonQuery()
                con.Close()
               
                Response.Write("file is inserted")
            End If