There are a lot of Howtos telling you how install Cyanogenmod on your phone, but most of them assuming you are using Windows. I kicked out my last Windows PC years ago so thats not an option for me.
Luckily I could combine different posts to get it working for me. Which made me even more disturbed was the fact that every how to hosted their own zip files with the images that should be transmitted to phone or even installed on your computer.
I tried to find the original websites and download the stuff from there instead of trusting that the images are ok. I would like to spend a little bit more time to find the correckt image from the offical site than trusting someone I don't know that he didn't installed a backdoor in my image :P
Download the following files
connect your phone to your laptop with an usb cable.
press vol down + center + power for 10 sec to enter odin mode
extract the recover.img if the rommanager was delivered as a rar file and flash the recovery loader:
heimdall --flash recover.img --no-reboot
after the progress bar is full, diconnect the device and remove the battery or the image is deleted imeadatelly after the reboot and you have to try it again.
put the zip files for cm and google app to the phone. E.g external SD card.
press vol up + center + power for 10 sec until it reboots into the recovery loader
make a factory reset install from zip install cm (you need to browse to the directory where you put them) install google