I assume you're planning to use my library? If so, definitely take a look at the documentation in the source code. After that, if you have any specific questions, feel free to respond here and I'll try to answer them.

I've seen many of your raycasting programs and they are very impressive. I just have plans to make an fps or open world sandbox game, but I dont know where to start.

I think the best way to start is to get the library up and running with your own code and play around with the basics like movement and collision with walls, and maybe placing some sprite objects in the map.

I've made many advanced sprite-bssed games. I'm just looking to learn how to start raycasting.

I want to learn the basics of drawing walls, wall collision, and sprites in the raycaster.

I've covered all of those things in the roughly 200 lines of documentation I wrote in the library. I can't help much with general questions like that here, but if there's anything specific you're hung up on, I would be happy to help.

Okay,first of all how do I draw walls?