There are many informations about functions and types over the internet. I decided to share my own knowledge and understanding of how functions work. It might help users here who are not sure about their type, or have trouble understanding functions. I tried to make clear and short description. If you guys will like it, I could add more about functions and types. This description is about Se/Ne types and their differences. If anyone want's to correct, or add something feel free to do it.
As I understand it, cognitive functions are the way one perceive the world and relate this perceiving to his thinking/feeling process. So the first sensation comes out a)from the extarnal enviroment via your 5 senses - this can be both Se and Ne, only the difference is the sensation of Ne type is not direct, the Ne relates a sensual experience to other experiences, patterns, or relationships, but this could not exist without the 5 senses processing the reality. Based on connections between objects and patterns the type assumed the object's future potential. The potential is what interests Ne users. The Si leads its role via relating current events to past events, for example "The smell of flowers here reminds me on my mom's parfume" could be an Si+Ne/Ne+Si statement. The processing of reality of Se/Ne type is objective. The Se type views the reality directly, doesn't work with patterns, but with objects themselves. For Se the object itself creates the reality, for Ne the connection between objects creates the reality, while the objects have the secondary role in the process and the connection created between them is more important. Se dominant users are highly aware of their physical environment and can quickly react on immediate changes in physical reality. They see the world in motion and they are aware of how they might effect it.
The Ni in Se types leads them to feelings of insecurity and doubt of themselves, or their enviroment. They might put simple ideas to a nonsense tests, when they are led by their doubts. The unhealthy Ni in dominant Se types can also lead them to believe they have "super powers" , or are "mystic visionaries". The unhealthy Si in dominant Ne types might lead them to be overly possesed with their body, health, symptoms, or unusual fear of physical challenges they've never experienced before.