One way to use play store is to download Bluestacks to your computer if you does not want to instal it to your jolla.

http://www.bluestacks.com/

One way to do it:

1. Download Bluestacks and install play store
2. install Apk Share and ASTRO file manager
3. Install the program you want to use in your jolla
4. Backup the program with apk share
5. move the apk file(location: /sdcard/apkshare) with file manager to a place your computer can see it


Edit: You can backup applications with astro file manager but it did not work for me in Bluestacks.