SQL Server, Convert Military to Standard Time

Here is my current SQL:

SELECT (startDate + ' From ' + startTime+ ' To ' + endTime) AS FullTime, dateTimeKey
FROM DatesTimes
WHERE DatesTimes.reservationKey = 79

startTime and endTime are being stored in the database as Strings.  The hold time values in hh:mm military format.  I would like to pull these values from the database and store them in FullTime but having a standard time format rather than military  (with AM or PM showing).

I tried this, but it didn't work:

SELECT convert(startTime, 108) AS Starting, convert(endTime, 108) AS Ending,
(startDate + ' From ' + Starting + ' To ' + Ending) AS FullTime, dateTimeKey
FROM DatesTimes
WHERE DatesTimes.reservationKey = 79

Any help would be most appreciated.