Giant's Secret Codex Of Mastery-Take it to a certain NPC to enchant skills.

How to get this book?

With NPCs inside Fortress, u have to Own a fortress to have acess to the NPC.
And you buy with Knight Epaulettes (don't know how u catch then)

When my clan have CH and Castle,do we can own a fortress too?

yes

if you have a castle, you can't own a fortress but you can have a ch

No Ivor, u can't own a Fortress and a Castle, but the Fortress receive direct "orders" from the castles, only not, if they declare independence from you. I think u can buy in the fortress that you "control"
Or no, I'm just thinking about it, my server don't get fortress and these many things in CT1 implemented

fortresses are added from IL

yes but at il u cant siege them

how is this diferent from bog? and why are there 3 type's (i think) of them? how u use them? thell me all about this items

there are boocks for normal enchantment
for blessed ench
and skill enchantment route change

im using only the normal ones and the change route ones(sometimes)

here is what i found on google

Safe Skill Enchant
Failing a skill enchantment does not decrease the enchant skill level.
The amount of SP and Exp. consumed is three times greater than that of a regular skill enchant.
Giant's Codex - Mastery is required.

Enchant Route Change
The skill enchantment route can now be changed to different route.
The skill enchantment level has a chance to decrease up to three levels when changing the skill enchantment route.
Giant's Codex: Discipline is required, along with some SP and Exp. consumption.

Skill Un-enchanting
Enchanted skills can be un-enchanted one level at a time. Some of the consumed SP will be returned.
Giant's Codex: Oblivion is required.