I'm having trouble understanding the levelling and perks system. For example I'm on level 26 of conjuration and to get the summoner in the conjuration skill tree I need to reach level 30. Now I know by using my conjure familiar it boosts my levels up. So I take it that if I keep using it all the time then I will eventually get to level 30 and unlock the summoner skill. so is a perk only used to open up a new skill like illusion or alternation for example and that is all. They have no other function once that new skill tree has been unlocked. Well that's what I assume anyway. So is that right. Please help.

If its already been asked many times then I'm sorry but I'm in my phone now so can't search the answer. So could someone give me a quick lesson please.

Each skill in a tree has a level requirement before you can spend perk points on it. When you reach the level requirement for a specific skill, it doesn't mean you automatically get that skill. For instance, you want the summon skill and since you have level 30 conjuration, you are able to activate it. You must use perk points for that.

Skills basically act as experience points in this game. They also serve a dual purpose of limiting what perks you can achieve in the chosen tree based on the skill level (so you can't have the top end perks without using the necessary skills).
The trees usually follow some order requiring prior perks and a certain skill level to allow you to purchase them (for example summoner requires novice conjuration AND 30 conjuration skill, whereas Twin Souls for example would require 100 conjuration, Elemental Potency AND Dark Souls before you can put points into it).
Hope this helps.

ah right I get it now. Many thanks for that my friend. now back to playing this awesome game again.

the new level up and perk tree is cute but with the clunky controls for pc and huge leap from tradition its kinda like having a "wth is this" moment every time