multiple user logins in jmeter

I just implemented this using jmeter for an app that uses Spring Security (It would be very similar to PHP). This is fairly straightforward, basically:

1) Create a new CSV file using a text editor
Ex: CSVSample_user.csv

   username1, password1
   username2, password2

2) In jmeter, create a CSV Data Set Config element

  Thread Group>add>Config Element>CSV Data Set Config
  => Assign variable names (see image)

3) Create an HTTP Request element

  Thread Group>add>Sampler>HTTP Request
  => Create a POST with parameters, have the variable you created 
     put the values for the parameter. (See bottom image).

NOTE: There are other elements you need, such as cookie manager, etc. Also number of threads needs to be set to the number of login users.