String dt = "10/1/2009 2:22:14 PM";
DateTime myDT = DateTime.ParseExact(dt, "M/d/yyyy h:mm:ss tt", null);
Most important step is to create a correct parsing string ("M/d/yyyy h:mm:ss tt")
Below are some useful parsing string information
d - Numeric day of the month without a leading zero.
dd - Numeric day of the month with a leading zero.
ddd - Abbreviated name of the day of the week.
dddd - Full name of the day of the week.
Fraction of a second. The more Fs the higher the precision.
h - 12 Hour clock, no leading zero.
hh - 12 Hour clock with leading zero.
H - 24 Hour clock, no leading zero.
HH - 24 Hour clock with leading zero.
m - Minutes with no leading zero.
mm - Minutes with leading zero.
M - Numeric month with no leading zero.
MM - Numeric month with a leading zero.
MMM - Abbreviated name of month.
MMMM - Full month name.
s - Seconds with no leading zero.
ss - Seconds with leading zero.
t - AM/PM but only the first letter.
tt - AM/PM ( a.m. / p.m.)
y - Year with out century and leading zero.
yy - Year with out century, with leading zero.
yyyy - Year with century.
zz - Time zone off set with +/-.