Use OpenXML to modify Word Doc

I have a Word Document stored on a server I wish to use as a template. I need to replace certain text with data from a database.

The two issues I have are:
No office on the server to use Microsoft.Office.Interop, and I cannot save any documents to the server.

I think I am on the right track, but cannot come up with a viable solution. I am thinking my best route is to read into memory and use a byte array to allow the user to save the file.

I was doing something like this, but am currently stumped.

 Dim path As String = HttpContext.Current.Request.PhysicalApplicationPath & "Letters\Test.docx"
            Dim docBA As Byte() = File.ReadAllBytes(path)

            Dim wordDoc As WordprocessingDocument = WordprocessingDocument.Open(path, True)
            Using (wordDoc)
                Dim docText As String = Nothing
                Dim sr As StreamReader = New StreamReader(wordDoc.MainDocumentPart.GetStream)

                Using (sr)
                    docText = sr.ReadToEnd
                End Using

                Dim regexText As Regex = New Regex("FIRST_NAME")
                docText = regexText.Replace(docText, "TESTING!!!")

                Dim sw As StreamWriter = New StreamWriter(wordDoc.MainDocumentPart.GetStream(FileMode.Create))
                Dim modBA As Byte()
                Using (sw)
                    sw.Write(docText)
                    modBA = sw.Encoding.GetBytes(sw.BaseStream, 0, sw.BaseStream.Length)
                    HttpContext.Current.Response.AddHeader("content-disposition", "attachment;filename= DownloadSample.docx")
                    HttpContext.Current.Response.ContentType = "application/octectstream"
                    HttpContext.Current.Response.BinaryWrite(modBA)
                    HttpContext.Current.Response.End()
                End Using