How do I find the position of a space in a string as in FIND(" ",C3,1)?
Use FIND: FIND(" ",C3,1).
Yes, I simply repeated your formula (even without replacing argument separators to universal ;). Just because it does what you want: returns the position of the character. Your question lacks any detail that could clarify why the formula doesn’t suit you. Edit the question to make your question clear.
Note that for a formula to be interpreted and calculated, it must start with an equals sign. Otherwise it will usually be taken as plain text and returned verbatim.
f you get an error from your formula, the cause may be what Mike indicated above. Try to replace the two commas. Semicolon always works.
Comma can only be used for parameter separation if Calc is configured to use period character as decimal separator.
Re Comments: The help prompt provided when you enter FIND uses commas as delimiters.
The help prompt provided when you enter FIND uses commas as delimiters
Yes, that’s because your locale uses commas. unfortunately, it’s a historical fact that someone decided that different locales should use different separators. That’s why I can’t just copy your formula using commas and use in my spreadsheet, because your locale uses non-standard separators; but if I paste my formula (with standard ones), you would be able to use it as is 
After further investigation I found that although the format ‘=FIND(“x”,C3,1)’ works for many if not most text characters it does not work for space characters (" ").
However the format ‘=FIND(CHAR(160),C3,1)’ does work when trying to locate a space in a string.
As a further note the content in question was copied and pasted from the web into the spreadsheet which may be significant.
CHAR(160) is a non-breaking space, not a normal (word separating) space but what you might use e.g. for thousands separator or between digit groups in a phone number, to avoid wrapping to next line in the middle of the number…
While I appreciate that two people tried to help me I cannot help but note that both first set out to show that I had done something wrong rather than assume that I had followed correct procedure and that the result was not what could reasonably be expected. This is called “fighting the question”. I had no reason to suspect that the data, which was simply a list of first names and surnames, contained any unusual characters. However I now know to check for non-printing characters in the event of failure or unexpected results.
This is not “fighting the question”. This is “avoiding guessing”. It’s your duty to try hard to ask good questions, and showing your flaws is helping you much more than trying to answer a question that could turn out to be absolutely different. “Assume that I had followed correct procedure” is only “simple” for those who know little about the topic, and thus only can imagine one “correct procedure” for one application of the procedure. Those who try to answer usually can imagine several valid applications, and several procedures for each.
E.g., one assumption was that you forgot to use the “=” - absolutely valid assumption, because many novices may miss that. You think that if’s “fighting”, because in your mind, forgetting the “=” is something wrong; while not knowing different whitespace characters is OK for you. This is doublethink 
While I appreciate that two people tried to help me I cannot help but note that both first set out to show that I had done something wrong rather than assume that I had followed correct …
Well, you asked a question because you did not achieve a proper result. A mistake must be somewhere…
Our objective is not to place any blame, but to find a solution. Helpers should start with “most likely suspects”, and with the lack of detail here, we start with the basics.
- Had you explained what you got (
#VALUEerror message or wrong position returned), we would know that formula was OK. We could then have proceeded towards content deviating from appearance, and suggest other paths to investigate. You determined this by yourself. Good job! - Had you also attached a file displaying the problem, it would most likely have been a matter of minutes’ work to locate the cause of your issue. We’ve been there
Now, if you will: click the “tick bullet” at your answer to mark the issue solved.