Look at online tutorials. Even better, try to find a small project to do and get to it. Use online reference manuals and tutorials to understand what comments to use.
What language is a difficult question. It all depends on what you want to achieve. Some languages are better than others for various tasks. For web programming, you'd need HTML, CSS, JavaScript. For Windows desktop, C# is pretty cool. For high-performance jobs, C/C++/Rust is the way to go. If you want to exploit a huge range of existing libraries, Python has it for you. There is plenty more languages, like Java, Go, various scripting languages like Bash, PowerShell, Lua, etc.
Try to find out what interests you and pick a language accordingly. Many techniques are transferable between languages, though.
I would learn C, then C++ a bit, or would go straight for Rust, which aims to replace them, then go for some managed language like C#, Java, or Python or Go.