Let me explain you in detail the different phases in load 
testing:

1.create test script using VIRTUAL USER GENERATOR(VuGen), 
and enhance your script by inserting checkpoints,adding 
loop/conditional statements/logic based on your requirement,
parameterizing the test for multiple set of data.
You can also run the script in VuGen for debugging purpose.
2.create scenarios using LoadRunner CONTROLLER.Edit load 
settings,run-time settings, stop settings and configure the 
load machines to generate load (vusers) and run the script 
for different number of Vusers(as per your requirement).
Monitor different graphs like Transaction response time, 
avg.transaction response time,hits per seconds,error 
statistics ,throughput,window resource,web resource,data 
resource, web resource to analyze the performance of your 
system/application, server response time,how many 
transactions passed or failed , CPU/DISK or MEMORY 
usuage ,etc....
3. The errors could be HTTP errors like HTTP 
500,501,502,503,504,505,509 etc......... i.e. internal 
server error,gateway timeout, service unavailable,etc....
 

Hope it Helps!!!!!!!

Prasu!!!!

1.Planning the test
2.Creating the Vuser script
3.Creating the Scenario
4.Running the Scenario 
5.Monitoring the scenario
6.Analyzing the test results.

1.Understand the Architecture(high Level) of the 
application under test
2.Planning the test
3.Creating the Vuser script
4.Creating the Scenario
5.Running the Scenario 
6.Monitoring the scenario
7.Analyzing the test results.