Are you talking about junk code that will get modified later or obfuscating your code? It's a yes for either, though you'd need to learn the language first.
If you want junk code so you will modify it later, it depends on how you will modify it. But you can just fill it with whatever bytes you want, unless it's going to be run while it's still junk, then you'd obviously make it so it will still execute successfully.
For obfuscation two simple techniques are to add the junk code throughout the real code and just not running them (most obvious way to do that is simply jumping them), or add code that will be run but does redundant things/changes. You could also do code morphing, to add another degree of complexity (though would need that section to be writeable).
If you want junk code so you will modify it later, it depends on how you will modify it. But you can just fill it with whatever bytes you want, unless it's going to be run while it's still junk, then you'd obviously make it so it will still execute successfully.
For obfuscation two simple techniques are to add the junk code throughout the real code and just not running them (most obvious way to do that is simply jumping them), or add code that will be run but does redundant things/changes. You could also do code morphing, to add another degree of complexity (though would need that section to be writeable).