Enchanting works in the following way...
1. Disenchanting
To disenchant is to learn the items ability. Basically if you find a piece of armour that increases your stamina by 20 points and you disenchant it, you learn the enhant to increase your stamina which you can then add to your armour peices. Disenchanting an item will destroy it so beware.
2. To enchant....
To enchant you need a learned enchant (see above), A filled soul gem, and the item you wish to enchant. Choose the item and soul gem. The larger the soul gem the more powerful the enchant will be. Also the higher your enchanting skill the more powerful the enchant will be. For example a lesser sould gem may only increase stamina on armour by a maximum of 5 where a grand soul gem may increase it by 15. Where at a higher enchanting level this may be 20.
To fill soul gems use a spell called sould trap when you have an empty soul gem in your inventory.
Or you can find weapons with this ability as an enchantment or enchant weapons with this yourself (providing you find a weapon with this enchant, then disenchant it and stick it on the weapon of your choice)
Hope this helps
Mickage