how to store word file as binary data into sql server

Easy!
Create your table field as VARBINARY(MAX).
Read the file as a sequence of bytes (either direct from your Upload control (if this is web based) or by using File:

byte[] bytes = File.ReadAllBytes(path);

Then just insert it with a parametrized query:

using (SqlConnection con = new SqlConnection(strConnect))
    {
    con.Open();
    using (SqlCommand com = new SqlCommand("INSERT INTO myTable (myDocumentColumn) VALUES (@DOC)", con))
        {
        com.Parameters.AddWithValue("@DOC", bytes);
        com.ExecuteNonQuery();
        }
    }