Hello, I´m Pelias. I´m a spanish amateur developer of games. Excuse me if my English is not very good I help myself with a translator online for the phrases that I  don´t know say . I am not very sure of since beginning, so I will begin for giving a general idea of my game. It´s my first game. After doing some tests I have decided to do a simple system, to give my first steps in this area.
New fantasy is a tradicional game of epic fantasy , with use a sistem own , called Mirror System. It´s easy. All the attributes can have a value from 1 to 8 and the skills go from the 1 to 16. To test skill you must throw 3d6 and must add to the result to the sum of the punctuation in the skill and to the punctuation in the corresponding attribute. If the final number equalizes or overcomes a difficulty imposed by the master, the test excels itself.
Whenever it goes out 6, it takes only this in view of and throw it again adding 6 and the new result. At any time in that, in the dice in the table, which you have used for this test, two go out some, the test fails automatically (I don´t know how to say "pifia" in English)
Also the system uses a type of die for every part of the game.
The d4 is for the creationg of characters, the d6 is for skill test , d8 is for combat...It looks especially, to be functional, and that all the concepts are understood easily
To seeing that it looks like to you this first information, I will be commenting as it should have more written

Why is a d8 used for combat and not a d6?  Isn't combat a test of skill?  How does combat work?

I'm also having difficulty understanding what you are trying to say in general.  Let me get this right: when you make a skill test, do you roll 3d6 and then add a skill bonus as well as an attribute bonus, and then compare it against a target number?  (Example: I'm jumping from rock to rock in a ravine.  The difficulty is 14.  I have +3 agility bonus and a +2 bonus from my jumping skill, therefore 3d6 = 10 +3 +2 = 15; I make the jump.)

I hace decided apart the combat of skills for be more clean. If you use only d8 , you haven´t serch the dies that you need, you put the dies of 8 , in front of you and you avoid complications. I am defining the rule of combat but I want separate it of skills.
Respect the skills is how you say, but you haven´t +3 or +5 . You have directly 3 or 5 and you add it to the throw

I think I get it.  Since skills go from 1-16, they have a greater impact on the die roll than attributes.

yes exactly