I picked up an older Ender 3 for my grandkids looking for info , upgradable? user manuals
Marlin ver 0.0.5 may 30 2020 Ender-3
any help or a point in the right direction would be greatly appreciated.
Hello !
the ender 3 is a good but old printer. It’s only my opinion but I don’t see you should try to upgrade it as it’s not worth it.
If you still want to upgrade it though, one of the best upgrade is the CR-touch/BL-touch, it allows to get a leveling on the bed 
It’s not that difficult, you then have to flash again the firmware though 
Ender Series Firmware Download | Creality 3D Printer Firmwares
You then have the 4.2.7 motherboard (faster and quieter) or even the sonic pad (to get Klipper) but the difficulty starts to increase
Thank you for your help think I am just going to leave it as is for now. what software would be a good choice for someone just starting out?
We use Cura for the slicing software as it is easy to use and have flashed the latest Creality Marlin based firmware onto ours. Flashing is actually very and getting a 4Gb or 8Gb micro SD card was the biggest problem we had. The older machines could only read an SD card of less that 8Gb.
We use Cura for the slicer but the CAD software
Cura is great, we all started with it…A bit outdated though
Nowadays, we use CrealityPrint (slicer made by Creality for Creality Printers)
and concerning the firmware….Yes, it is pretty easy to do it (when there is no error) but I don’t see the use of it when everything is working perfectly. 