Exactly what does the 'No-Collide' tool do?
It makes an object not collide with something else, you can use the right click to make the object not collide with anything (except the map, it'll always collide with that)
You can left click an object and a second object, i've almost never used this, but i think it makes the two objects not collide with each other or something
I just use the right click method, you can right click the object again to make it collide with stuff normally again