Welcome to 0x00sec!
Knowing how to create undetectable payloads naturally requires you to understand how anti-virus software works so if you do not understand this then it’s pretty hard to know what to do. I’d highly recommend you do some reading on not only this but also on how the Windows operating system works at a relatively low level, i.e. knowing the WinAPI, memory, special objects such as the registry, file formats, disassembly and debugging, etc.
I have a repository on the GitLab that has some resources on how anti-virus works and past methods discovered used in an attempt to defeat detection so if you wish to see them, register an account at https://gitlab.s-3.tech/ and then head over here: https://gitlab.s-3.tech/93aef0ce4dd141ece6f5/Resource-Dump/tree/master/Antivirus. If there are any issues accessing the repo, just message me your username and I will add you as a guest.
Discussion on this would be incredibly extensive which is probably better on a live chat medium such as our IRC at irc.0x00sec.org:6697+ where @Leeky and I are always actively discussing malware . If you just want to do it here then that is also fine.