Upgrading from Snow Leopard (10.6.3) to Mountain Lion How do I upgrade to Mountain Lion, and then to El Capitan?

I just installed Snow Leopard (10.6.3). I have tried to upgrade to Mountain Lion, but that requires that I have 10.6.8 or higher, which I don't.

Also, I have for the last 2 days, checked for any updates and have installed whatever was available. I am now confused on what to do.
Step Zero: consider your backup and if you want to do a two-step upgrade per http://apple.blogoverflow.com/2015/09/back-up-then-step-up-to-el-capitan/

Step One: Download the 10.6.8 combo updater at https://support.apple.com/kb/DL1399

Step Two: Use the App Store to install OS X and be aware you might need to jump 10.7 to 10.8 to 10.9 to ....