why I can't find files with substrings with "find" command

I am trying something super basic but I don’t get why my find command cannot find a substring. Here is the output

15:04b0 gmmo@mylinuxbox ~/test_search> cat somefile.txt 
find substring here!
15:04b0 gmmo@mylinuxbox ~/test_search> find . -name "*sub*" -print
15:04b0 gmmo@mylinuxbox ~/test_search>  

Does the string inside the quotes need to be regex?

I am following this thread

Find all files with name containing string

What is the proper syntax to find all file containing a sub-string case insensitive in it recursively ideally?

>Solution :

Dont be confused by filenames and text content:

find . -type f -exec grep -il 'sub' {} +

or simply:

grep -ril 'sub' .

or with ack aka beyond than grep (faster):

ack -il 'sub'