Hi there!
I have seen in earlier post that we can alter a value of an Account's field
through a workflow rule of a Case concerning that Account. I cannot
understand how I can do this, influence between two entities using a
Workflow rule.

Also, I don't understand the use of Post Url Action, athough I read about
it...

Can you help me and give directions or examples?

Thank you
Elena

When you add the "update object" action, it will give you
a pick list of objects you can update from within that
object (the object you are writing the rule for).

For example, when you select "Insert Action / Update
Object" within a case workflow rule, you can update
fields on the Case, Account, Contact, Contract, Owner, or
Subject entities.

When you pick the object, the list of fields you can
update appear in the fields below.

Post URL is the most powerful of the workflow actions,
IMO. I'm just now implementing my first one. But
basically, you can pass any fields from that object (the
case, for example) to a web page, and then you can
basically do whatever you want.

Of course, the trick (at least for me) was constructing
an asmx file (C#, but you can use VB.net) that worked...

Cool stuff, there is an example somewhere on
TechKnowledge.

HTH,

Dave