How would I select everything from last month in a sql statment my cell has a time stamp in it

SELECT DateTimeStamp
from Get_estimates

Ouput

[DateTimeStamp]
2008-02-28 11:39:35.247
2008-03-09 13:15:12.513
2008-03-09 13:16:53.700
2008-03-26 13:30:20.077
2008-03-26 13:30:51.810

So the output should be
2008-03-09 13:15:12.513
2008-03-09 13:16:53.700
2008-03-26 13:30:20.077
2008-03-26 13:30:51.810

right?

I want to display all the orders from last month so

SELECT *
from Get_estimates
where DateTimeStamp = [lastmonth]

Ok, please give me sample Data and your desired output