Here is the online help files for Songwriter 2012 Mac

https://usermanuals.finalemusic.com/SongWriter2012Mac/SongWriter_Left.htm?Musicxml#CSHID=1|SkinName=NewWindow 

It supports MusicXML 1.1-2.0 import/export. You will need to use a scanning app that supports MusicXML such as SmartScore X2 Pro which can edit files before import

https://www.musitek.com/smartscore-pro.html

or Music to XML which does not support pre-editing.

https://www.musitek.com/m2xml.html

Songwriter 2012 is no longer supported after OS 10.9 Mavericks but will probably work through El Capitán 10.11. It does not work in Sierra 10.12 or later.

https://www.finalemusic.com/blog/finale-printmusic-os-x-10-11-6/

As Mike H says, you will not be able to scan within SongWriter. You will have to use an external program to scan and convert to XML, which you would then import to SongWriter. The programs that do not support editing before exporting are, IMNSHO, worthless. And in fact, since SW lacks so many of the features of Finale, I would rate that at about the same.

I'm not badmouthing scanning. I have used this process on hundreds of scores, from simple piano to multistaff choral and accompaniment. From your earlier questions, I'm thinking that you are a fairly new user, and you want to stick a multiverse hymnal page into a scanner, and have good sheet music come out. Ain't gonna happen. For one thing, lyrics and other text are really poorly recognized.

My work flow is this: Scan the music. In SmartScore Pro, recognize the scan without text or lyrics. Make the corrections (and there are always corrections) in the SmartScore program. Export the XML, and import it into the full Finale. Continue editing. When the notes are good, enter the lyrics, and finish up.

Only experience will teach you what to edit in SSP, and what to do in Finale. And currently, I would not recommend buying SmartScore if you are running Mojave or Catalina. There are problems. We're waiting for the new, 64-bit version to be released.

>And currently, I would not recommend buying SmartScore if you are running Mojave or Catalina. There are problems. We're waiting for the new, 64-bit version to be released.<

Amen!

To which I'll add that Songwriter will not work in Mojave or Catalina (or Sierra or High Sierra) either. 2012 was its last year. Finale 26 is the only MakeMusic product for the Mac supported on the latest operating systems.

Thankyou for your advice.    I have mac OSX el Capitan version 10.11.16..... song writer seems ok with my Mac

In that case, you'll probably be OK with SmartScore. But I'm not sure if SW2012 has all of the editing features you will need once you import the XML.

Here's the comparison chart from 2014 and the last one that included Songwriter. Much of it is out of date and some is just plain wrong. The mentioned iPad app — forget about it.

https://wpmedia.finalemusic.com/wp-content/uploads/2015/07/finale-2014-product-comparison-chart-2.pdf