li'l help please

I need some help on something here, for a map I'm makeing I need to have some units controlled by an AI and I need these to do specific things but I don't know how to write in Jass and dont think I can make the needed unit orders with normal triggers.

Specifically I need 1 type of unit to pick the closest target building owned by an enemy and attack move towards it ,then when its dead I need it to move on to a new one.

I can get this to initially work with normal triggers but once the first structure is dead I can't get them to pick a new target, they either just stand there or move back to where they were built.

And one other type of unit needs to merely patrol around the area in which it is built (this ones pretty simple and I think I can figure it out)

You will not need ai scripts but you should learn JASS and do it with custom text triggers