Workflow: AND-condition

[JDAEMS]

Hi,

I have a workflow with 5 sessions in it. But I don't know how the make the workflow with these sessions the way I want. I'll explain:

The sessions have a certain order in which they have to be executed.

For example:
When session1 AND session2 are both finished, start with session3.
When session3 AND session4 are both finished, start with session5.

I am a beginner in Informatica and I am sure this is easy to do. I just don't know how.

Should I work with a decision task? How does it work? What are the steps to accomplish this?

Thanks for the information.

Kind regards
Jelle