How do I find the creation time of a file?

You can't - it isn't stored anywhere. Files have a last-modified
time (shown by "ls -l"), a last-accessed time (shown by "ls -lu")
and an inode change time (shown by "ls -lc"). The latter is often
referred to as the "creation time" - even in some man pages -
but that's wrong; it's also set by such operations as mv, ln,
chmod, chown and chgrp.

The man page for "stat(2)" discusses this.