I believe you have finished building HelloWorld Project, as per previous Oracle BPEL Training article.
Lets do the testing to see Oracle BPEL HelloWorld in action.

Step 1. Navigate to BPEL Control and select Dashboard Tab. You should now see project HelloPassiWorld.

Step 2. Click on HelloPassiWorld.
Step 3. In the input field, enter " SOA World"
Remember that we will concatenate a text to the value entered in Input Variable.
Following that the stage_2 would assign the modified input variable to output variable.
Step 4. Click on Post XML Message


Step 5. The results of the test are


You can see that result is now Hello From Passi to SOA.
Effectively, we manipulated the inputVariable and then assigned the manipulated value to outputVariable[result].
The entire exercise for developing and testing HelloWorld in BPEL will take just 2minutes provided you know the steps.