When I go into my apple software updates on my OSX 10.6.8 computer to update to an OSX 10.9, the computer tells me that I do not have any new updates. How can I update to OSX 10.9 if it does not give me that option?
Mac OS X Lion - 10.7 was (is) a paid upgrade. From there, you can then ride the free major upgrade train as far as your hardware allows.
I’ve heard of people jumping to ElCapitan, but never experienced it since I have lion digitally as well as on a USB key so I just rolled that path in the past.
You may run into issues, so feel free to ask a specific question if you run into a specific block knowing you can’t just upgrade in one step.