A noob question...

I'm learning how to build now and my first project is a playhouse. My problem is that when I linked the scripted door to the house, the door stops working (doesn't open and close anymore). How can I linked the door and at athe same time have it working when clicked? Thank you very much.

Some doors can be linked, some can't, depending on the script. And if they can be linked, they'll either need to be the root prim (last prim selected before the link operation) or, more likely, need to *not* be the root prim. A common example of the latter is the "standard" Timeless Linked Door from Timeless Prototype, found in the scripting library:

http://lslwiki.net/lslwiki/wakka.php?wakka=LibraryTimelessLinkedDoor

By the way, if a child-prim-based script is in a door linked as root prim, most often it will either do nothing or--less desirable--it will rotate every other prim in the linkset.

This is a very annoying thing I run into at times as well. Doors stop rotating after being linked, or rotate in an entirely wrong direction, over another axis. So I generally check if a door will rotate within the link set, or otherwise just won't link it at all.
Making sure the door has a unique name (so not "object" within the linkset often helps too, by the way, but it's still not failsafe for some reason.

The drawback of a non-linked door is that it sometimes repositions itself, if an avatar is standing in the position where the door is opening or closing. Even when the door isn't physical (mine never are, but this still happens).
A solution I found to this, is making a custom-fit panel around the door, and linking the door to that, making the panel the rootprim (and hope the door still works, lol).
Other solutions could possible be to make the door phantom right before it opens, and non-phantom right after it's closed. Or to force the door to reposition itself right after it closes. I haven't tried either of these yet though, but at times it would be convenient I think.

Anyway, do not worry if parts of a structure are not linked. It´s maybe less convenient, but it´s certainly not the end of the world

Most doors allow you to edit the scripts so you can change direction of rotation,sliding,distance etc. the main thing to remember to stop them moving once used is to reset the scripts once you have placed them as most remember th position where they were rezzed not where they are eventually placed

As stated before a lot of doors cannot be linked as their scripts will then act on the whole building meaning your door will stay still and your whole house will open. Once you have the door where you want it you could try locking it in place but this again depends on the script