File mafile
myfile = SD.open(
Ummm...
If you are going to use functions of the SD library, don't you think that you should #include it (and a begin in setup is missing). My advice is to load and run some of the examples included with the SD library to get more understanding of its use. Write a sketch that just reads a text file and displays the content in the serial monitor. It is a short step from there to writing the data out to the HC05.