You can use the block:
Be aware that the file will be recorded into the ASD not into the "Gallery" of your phone.
Then to move files into specific directories you'd better have a look to @Anke 's posts on the related topic (help on file saving on Android devices) or to the following thread:
Where are canvas files saved to by default when using the block call-Canvas.SaveAs?.
Lastly you can also get info on file saving by referring to @Taifun's extension (com.puravidaapps.TaifunFile.aix), or to @anke's extension (de.bodymindpower.MFile.aix), as well.
Best wishes for a successfully app and for a great new year.