when pc's first became generally available, they tended to come with an operating system and a programming language, which was basic.
Two or three Comprehensive manuals were supplied
Would suggest you obtain a copy of the Basic manual, from somewhere like ebay/computing /vintage where they are regularly offered inexpensively.
One sees unopened packs of dos manual offered which should include this.
An interesting aspect of basic, was that for commercial programming previously:-
one wrote a (source) program
input this to a compiler program which created a (semi-compiled) or (object(compiled)) program
if semi-compiled, input this to a consolidator program, which expanded source calls for pre-written subroutines and extra-codes etc.to create a (object) program
The object program is the final version that runs on the computer.
With basic, the source is written then input to the compiler which interpretes it and runs it then and there. Previously this method tended to be used with some scientific, as opposed to commercial, programming languages.
Here endeth todays history lesson. :-)
Perhaps others can recommend a website that offers a self-teach facility for basic.
Personally I find this method ok, but the problem is, a screen can only hold so much information and the necessary flipping back and forth when studying is much easier with a manual than with a screen.
Good Luck - Keep us posted