All you have to do is read the file into a byte stream
byte[] data = File.ReadAllBytes(path);
then use a parametrized query to insert it to the database. I would recommend you use a OleObject field type as otherwise you may find yourself out of space.
using (OleDbConnection con = new OleDbConnection(strConnect))
{
con.Open();
using (OleDbCommand com = new OleDbCommand("INSERT INTO myTable (myFile) VALUES (@FILE)", con))
{
com.Parameters.AddWithValue("@FILE", data);
com.ExecuteNonQuery();
}
}