Core and voice
Hello everyone! I am new on this forum (and new about useing hammer). I would like to ask you, how to add npc (for example glados's core) and voices for it (when i pick up it, drop, or plug in). I hope you will help me 
The entity to create a core is "npc_personality_core". Give that core a name.
Make a ambient_generic entity anywhere, give it a name, and make "SourceEntityName" the name of your core. Change SoundName to the sound you want to play.
And last, go to the core's outputs, add one. Choose "My Output Named" to be whatever, (OnHit, OnPlayerPickup, OnPlayerDrop, OnDeath, ect ect). "Targets entities named" will be the name of your ambient_generic, and the input is PlaySound. 
(Glados Lines
Wheatley
Cave Johnson
Caroline
Announcer
Defective Turret
Regular Turret
Cores)
Create an npc_personality_core and (assuming you want it to be Wheatley) name it @shpere. To male it talk, simply create a logic_choreographed_scene. Find the voice file from the scenes section and set everything up. The inputs should be pretty straight forward.
This
My explanation was how I do it. :p
I don't do things very good when I find them out by myself. 
I don't do things very good when I find them out by myself.
You're not going to learn anything if you don't search and find out yourself (I know you said you fail but its definitely not true). I suggest you start at the vcd https://developer.valvesoftware.com/wik ... phed_scene. Someone was nice enough to make this page: https://developer.valvesoftware.com/wik ... aDOS_speak. That page would get you through the process of the logic_choreographic scene. Wheatley will be a bit different of course - refer to a reply above which states you use a npc_personality_core.
If you still aren't sure: decompile one of Valve's maps to see what entities they have in order to get wheatley to talk.
What if you want custom speech for it? Then Yenwoods way is okay I think or can it be done same way as portal2tenacious told?
It's best to make a new scene for a big project, or use an ambient_generic for a small (single- or double-map) project.
The thing is: if you don't use a scene file, wheatley won't do any animations. I'm sure you can give Wheatley animations to play, but that is the whole reason for scenes and faceposing - he is given 'guestures' which blend together to make one animation to seem as if he is talking.
You could probably mimic this through some simple animations you can find out using the modelviewer and using an ambient_generic with a custom sound.