were can i find a blak soul gem???

ok, to get the Black soul gem you have to have Done the quest "Necromancers Moon"
From the mages guild......Then steal the guys note, it has instructions for the alter outside of Dark Fissure. Disregard the praying part.... place your grand soul gem inside of the alter and cast soul gem ...I think it only works on a monday night... (there has to bea light shining on it)

May I please ask a question regarding Soul Gems - I was wondering where I can find Gran Soul Gems?

When your level is high enough,almost in any cave

I'm currently level 11, is it high enough - Cause I need it kinda fast

Do you know where to find Azura's Shrine?

Yes, I know and I've been there - Can I find 5 of them there?

No, you can't.Did you complete the quest for Azura?The reward is Azura's Star:It's a RECHARGABLE soul gem,and it can trap grand souls (no human,sorry)

**Spoiler**

First of all, I've done the Azura's Shrine quest and gotten the ring because of the MQ's Daedric Artifact. And I need five Grand Soul Gems because I need to cure my vampirism, and the Witch said she would help me if I managed to get her five Grand Soul Gems...

Don't tell me you gave away Azura's Star!!!
Regardless,you might try shops.Maybe that Altmer in Market District has some.....
Otherwise you will have to wait until about level 20+

Any necromancer's altar will do - there are several around (mostly mage's guild quest related). You can convert a regular soul gem as specified above (except cast "soul trap" not soul gem). Then, cast soul trap on a human and kill them within the effective time of the spell and you'll have their soul in your gem!

to get grand soul gems. go to chorrol mages guild. there is a guy who sells them. he has 2 or three. i forget. then there is a display case with a few grand soul gems. dont mix it up with the one with the greaters. then there is a display cas in the arch mage's lobby in the archane university. hope i helped

There is Grand Soul gems in the meages gild