Use char inside another char

Using Arduino Programming Questions
1

How can I use const char* inside another char?

This is my demo code:

void setup() {
Serial.begin(115200);
}
void loop() {
  const char* myName = "John";
  char fullName[] = "My name is: ", myName;
}

Error message:

Arduino: 1.8.10 (Mac OS X), Board: "LOLIN(WEMOS) D1 mini Lite, 80 MHz, Flash, Legacy (new can return nullptr), All SSL ciphers (most compatible), 1MB (FS:64KB OTA:~470KB), v2 Lower Memory, Disabled, None, Only Sketch, 921600"

conflicting declaration 'char myName'
   char fullName[] = "My name is: ", myName;
                                     ^
charTestSLETDENHER:9:15: error: 'myName' has a previous declaration as 'const char* myName'
   const char* myName = "John";
               ^
exit status 1
conflicting declaration 'char myName'

This is just demo code, but I need to know how to do this, to use in another project, so it must be an char.

2

strcat() or strncat().

3

I just tried strcat:
This is my code now:

void setup() {
Serial.begin(115200);
}
void loop() {
  const char* myName = "John";
  const char* nameText = "My name is ";

  char fullName;
  strcpy(fullName, nameText);
  strcat(fullName, myName); 
  Serial.println(fullName);
}

But now I'm getting this error message:

invalid conversion from 'char' to 'char*' [-fpermissive]
4

fullName needs to be a char array, you forgot the square brackets. try char fullName[16];

5

It would behoove you to learn the difference between char, array of char, and pointer to char, so you can ask intelligent questions, using proper terminology.