Make the entire Internet your mentor. It's filled with information and answers to all sorts of questions. Look at some programming tutorials such as codecademy. Maybe find some books on computer architecture, learn about mathematics that might apply to computer scientists.
I would agree with using the Internet, though I would not limit to any particular site, tutorial, or guides. I personally learned most of the programming I know from Google searches on per-case needs - the easiest solution is find something you want to create - way back when my project was to recreate MySpace - nowadays it may be a mobile app, a web services, or whatever you desire - then start building it - as you need to accomplish something new, learn that bit. You can also escalate your project if you start off small and build it - such as if you want to create a multiplayer mobile app, there are a ton of steps you can break up into smaller projects to learn all the aspects.
I find that people who learn CS from non-top-tier-tech colleges or from books tend to be limited in their knowledge, relying more on books and reference sheets than stronger programmers who learned by trial and error. People who learn how to program from external sources tend to be more narrow in their programming styles, following a single type or development, programming, project structure, and even languages - many are so limited they struggle to learn a new language, when a stronger program can pickup new languages quickly and entirely new programming styles.
Of course this is limited to programming for the most part. If you are going to be more focused on another aspect, the approach may be different. Learning hardware is more hands on and is harder to do through Google searching - in this aspect of CS, I'd strongly recommend some books to assist - also taking apart and rebuilding a computer or laptop is always fun if you haven't done so.
There are also other aspects to CS - if you are more descriptive with what you want to learn HN may be able to give some better replies.
For what it's worth I never needed a mentor for CS related studies and I ventured as far as going through the Dragon Book which isn't usually freshman material. Thankfully CS correlates heavily with programming and for everything programming there are many good communities online waiting to help you out. You can post purely theoretical question on StackOverflow or other StackExchange sites and get a decent response pretty quickly.