Check if list contains element that contains a string and get index of that element

Check if list contains element that contains a string and get index of
that element

While searching for an answer to this question, I've run into similar ones
utilizing LINQ but I haven't been able to fully understand them (and thus,
implement them), as I'm not familiarized with it. What I would like to,
basically, is this:
Check if any element of a list contains a specific string.
If it does, get that element.
I honestly don't know how I would go about doing that. What I can come up
with is this (not working, of course):
if (myList.Contains(myString))
string element = myList.ElementAt(myList.IndexOf(myString));
I know WHY it does not work:
myList.Contains() does not return true, since it will check for if a whole
element of the list matches the string I specified.
myList.IndexOf() will not find an occurrence, since, as it is the case
again, it will check for an element matching the string.
Still, I have no clue how to solve this problem, but I figure I'll have to
use LINQ as suggested in similar questions to mine. That being said, if
that's the case here, I'd like for the answerer to explain to me the use
of LINQ in their example (as I said, I haven't bothered with in my time
with C#). Thank you in advance guys (and gals?).