You will need a font with the tick symbol within it. If you do not have Wingdings that is unusual, but I suspect you may be able to search for it and download it from the Net somewhere.
Check what fonts you have by running charmap. You can then use charmap to copy any symbol to the paste buffer and paste it wherever you wish.
Thanks Mosiac for this tip. You learn something every day! I have never known how to put the half symbol, so that's very useful. It only seems to work with Word documents though, can I put it in emails or on Answerbank?