A second to both NVDA and the mac screen readers. I use them both, as a totally blind computer user, and they both work well for me. If you'd like some tutorials to help get you started with NVDA, these are pretty good:
http://www.nvda-kr.org/en/

The presenter has a slight Korean accent, but his English is just fine, and you get used to it quickly.

I use two tools, one is Zoomtext which definitely isn't free and isn't the best screen reader, I use it for magnification.

The other one which I have been playing around with a lot and really like is NVDA. $1 It works similarly to JAWS, although admittedly I have next to no experience with JAWS. I simply can't drop the $1,000+ for JAWS Professional when there is a free option out there.

If you want a something like JAWS in the future you could get in contact with Rehab Services for the Blind in your state if you are in the US or a Lighthouse type organization. Both have been very helpful in getting equipment for me personally. However I won't even bother requesting JAWS from either because NVDA works so well for me. Hope this helps, good luck!

If you are on a Mac, it comes with voiceover built into the operating system which is a fantastic screen reader in and of itself. There are built in training tools, however I purchased braille books/manuals on it from the lighthouse here in San Francisco and am receiving technical training from the Department of rehab. I find it really quick and intuitive, and less prone to problems that I encounter with Jaws on windows. However, there are some compatibility issues with Google documents, and you currently have to use Microsoft office 2016 for accessibility, both of which seem to be more streamlined and windows. Office 2016 and further updates to Google docs are looking promising for the Mac thankfully.

If you are on a mac, there is a screen reader built in. I've not used it so cannot attest to.