No problemo, Bob. We all start off knowing nothing!
So, you basically have 2 kinds of software instrument; ones that play samples (i.e. recordings of real instruments) and ones that generate the sounds all in the software (like a virtual synthesiser that models the electronics of a real synthesiser).
Kontakt is a sampler.
Komplete is a bundle of NI's instruments
including Kontakt.
In answer to your question, you can download a free taster of Kontakt which should keep you happy for a while:
https://www.native-instruments.com/e...free-download/
You can also download a free taster of IK Multimedia's SampleTank, which will give you more variety of free sampled instruments:
http://www.ikmultimedia.com/products/sampletankcs/
Report back if you have any problems getting these to work