You can use the jewel of bless to bring your item to +6

The way to use a skill is to click your right cursor instead of your left when attacking. Your stamina will decrease but will regenerate after time. As for +luck don’t worry about the jewel stuff for now as you won't need sevensouls gold to know yet. Furyˇs Jewel and Chaos Machine Guide:  

Jewel Of Bless - Chance to Succeed: 100%

Items it can be used on: Any piece of armor, weapons, and wings. Cannot be used on satans, Angels, horns, dinorants and orbs.

How do I use the Jewel of Bless: Simply place the jewel on top of the item and drop it?

What happens when I use the bless: Your item will move up one level. This can be done only if the item level is from 0-5. You can use the jewel of bless to bring your item to +6; after this you must use the jewel of Soul. Examples of Blessing an item:

Blessing dragon armor 3+12 dragon armor 4+12

Blessing Chaos Dragon Axe 0+0 Chaos Dragon Axe 1+0

Blessing Satan Wings 0+4+luck Satan wings 1+4+luck

Note: The Jewel of Soul does not have a 100% success rate; Soul at your own risk. Items +luck greatly increase your chance to succeed.