So your problem is with Pathing? A fairly simple pathing method which most people use is this:
Create a Region at each point that the creeps need a new Move Order. So for example: Your path may look something like this:
S= Start F = Finish _ = Path | = Path . = Region
S___
|__F
So if he units had to move along the line, they would need a new Move Order at each turn.
You regions would be placed similar to this:
S__.
|
.__F
S and F would also be regions, to tell them where to move from the start and when they have reached the end.
The most basic method to do this using Triggers is:
Let's call the first region(.) R1, and the second region R2.
Events
Whenever a unit owned by PlayerX (owner of creep) enters S
Conditions
Actions
Order Triggering unit to Move to R1
Events
Whenever a unit owned by PlayerX (owner of creep) enters R1
Conditions
Actions
Order Triggering unit to Move to R2
Events
Whenever a unit owned by PlayerX (owner of creep) enters R2
Conditions
Actions
Order Triggering unit to Move to F
That's the basic idea of pathing. Sorry I couldn't help more than that, and I'm still not sure you're asking about pathing. Although I don't have access to World Editor right now.
Also you may want to finish up the pathing with a trigger to remove the creeps that make it to the end.
Hope that helps.