How to create an AppImage?

Hi, can you tell me the necessary steps (in detail please) to convert an app into the appimage format?

I use KDE Neon (based on Ubuntu 16.04), which only works with 64bit and there is no way to install 32bit old software like Adobe Reader for Linux.

The application I would like to convert (to use if needed) is Adobe Acrobat for Linux.

Get the Deb from here:

ftp://ftp.adobe.com/pub/adobe/reader/unix/9.x/9.5.5/enu/AdbeRdr9.5.5-1_i386linux_enu.deb

Dependencies for Adobe Reader

gtk2-engines-murrine:i386
libcanberra-gtk-module:i386
libatk-adaptor:i386
libgail-common:i386

Thanks so much.