Is there a post specifically on soul gems and how to make them, about the different kinds, uses, etc.?

Google, my friend. Though they aren't that complicated. You fill 'em up, use them to recharge weapons or make enchantments on stuff.

you dont make them you find them. in one specific area of the game you can mine them. the different types denote how powerful a soul they can contain at max. black soul gems are merely required to get the souls of humanoids(the 10 playable races).

http://www.uesp.net/wiki/Skyrim:Soul_Gem

Soul gems.

You do not make them. You buy or find them.

To fill them you cast soul trap on an enemy and then kill enemy. If you have a big enough soul gem the enemies' soul goes inside it. More powerful enemy=bigger gem. It is based on level but to give a rough idea....

Petty= wolves
Lesser= ice wolves
Common= bears
Greater= giants
Grand= mammoths
Black= humans(always a grand soul, from peasant to master vampire, always grand.)

Unlike previous ES games soul trap is not a touch spell. Its range is about the same as the flames spell. Now take your soul gem to an enchanter with an item to enchant. You have to destroy an item with the enchantment you want(lets say absorb health) in order to enchant something with that same effect. With weapons the bigger souls will give you bigger charges(more uses), and recharge better. With armor the size of the soul gives you better effects.

u dont make soul gems u find/buy them

there are different kinds, black-grand-greater-common-lesser-petty

some gems already come with souls, u can fill them with the enchant soul trap, with the conjuration spell soul trap also and u can use bound weapons with perks to also soul trap

they are use to lvl gear/weapons, also if u enchant weapons it uses magic charges, u fill the magic charge with the gems (soul gems get destroy after they are use)

*Spoiler* theres a quest that gives u a soul gem that isnt destroy afer been use (either black or grand)

hope this helpz

To fill a soulgem, have an active Soul Trap effect on something as it dies. If you have a big enough soul gem, the soul will go into the smallest applicable one you have empty. (This does mean if all you have is Grand Soul Gems, and you soultrap a wolf, you're gonna have a Grand Soul Gem containing a Petty Soul.)

The types are as follows, in ascending order. A soulgem can generally hold any soul of its size or smaller.

Petty
Lesser
Common
Greater
Grand

There are 3 'special' kinds of soulgems.

Black Soulgem - this is a Grand Soulgem that has been twisted by powerful necromantic rituals to be able to capture the souls of people as well as creatures and daedra. In the moral spectrum, it's generally considered to be an extremely evil thing, as this denies people their afterlife.
Azura's Star - This is a Daedric Artifact, created and empowered by Azura. It serves as a Grand Soulgem, but is not destroyed upon use of the soul, meaning you can use it again and again. It can only capture creature/daedra souls, like a normal soulgem.
The Black Star - This is a Daedric Artifact, created by Azura, but twisted by a powerful necromancer. It serves as a Black Soulgem that is not destroyed by using the soul within, so you can use it again and again. This is possibly the most evil artifact in the game.

A soul can be used (and thus destroyed) for the purposes of enchanted objects. Either to create them (providing the needed mystical energy), or to recharge a depleted weapon.

The most effecient way to fill soulgems is to get a powerful mundane weapon (like an Ebony Battleaxe), enchant it with Soul Trap for 1sec, and go around killing things with lots of soul gems in your inventory. If it somehow starts to run low on charges, just use one of the gems it's filled to give it several hundred more hits worth of charge.