Skills do not have an associated stat. The stat/skill combination is particular to the situation, and to be determined by the GM.
[#Guidance for GMs on appropriate stats, possibly rehashing info from ./stats]
Starting characters have experience equal to the total of their three mental stats.
Skills have several levels available:
Familiar
Trained
Skilled
Expert
Master
Legendary
Familiar means simply that the character is familiar with the idea of the skill and may therefore 'give it a go'. One need never have actually attempted to use the skill. For example, most people would be familiar with the Swim skill, whether or not they have actually entered the water. Only those who have lived their entire lives in an icy wasteland, or dry desert, might not be familiar with the idea of swimming. Similarly, isolated mountain or jungle tribesmen may never have considered the idea of riding another animal. In general though, most characters will be familiar with most skills (but pity the poor peasant who seeks to emulate the words of power he heard spoken by a travelling magician!).
A trained character may know the theory but have little practical experience with a skill, or have had a short or informal apprenticeship.
Skilled characters are proficient enough to earn a living using this skill.
The best around. If you want better you are going to have to look for it, and probably have a lot of gold.
Olympians. Compete for the highest honours in their craft.
Generational talent. Unsurpassed.
One character may have the swordsman skill and another a fencing skill, both to a Skilled level. The first will receive a +2 in combat when using all swords appropriate to the characters background. The second will receive a +2 in combat only when using a rapier (perhaps and/or sabre), but will have some knowledge of duelling etiquette etc.
Target number:
The target number for a simple task performed by a character with basic training in a skill would be around 4 - a task accomplished without effort by a talented (high stat) expert (high skill).
A one on the die roll is always a failure, although not usually with disastrous results. Remember that a character talented enough to accomplish the task without rolling need not risk failure.
A character who's stat+skill is _higher_ than the target number need not roll the die; the character can accomplish the task without effort.
Armour restricts skills involving movement etc.
EXAMPLE SKILLS
Ride Horse
The ability to ride horses. Will include some ability to care for horses on a day-to-day basis. While this skill may give some insight into how other beasts may be ridden, it is in no way the skill to do so. A more general 'Ride' skill would include no provision for the care, or foibles, of particular beasts.
Dodge
Use this skill instead of weapon skill when defending in combat. Also useful against ranged attacks the character is aware of, and other imminent .
Eldritch Chant
This is purely the skill of pronouncing the words of power with the spoken voice. It is not required for any kind of magic use, although many dedicated spellcrafters choose, or require it, it as the skill focus for their magic. It also impresses the yokels, for better or worse.
Climb
The ability to climb cliffs, walls, trees, ropes, etc.
Swim
The ability to swim. Waves per point, or something.
Shield Fighter
Use this skill when defending against attacks with a shield. Shieldwall tactics. Bonus on morale checks to hold formation.