How do I start this quest

Talk to Jensine at Jensine's "Good As New" Merchandise in the Market district.
I was wrong. Listen below

That's another tomb I think. If you're referring to the one near Leyawin, you go to it on one of the Fighter's Guild quests.

http://www.uesp.net/wiki/Oblivion:Amelion%27s_Debt

Thank you also is there a master alchemy set or is novice really as high as it gods

Yes, there is master alchemy gear. It can be found in random loot once your character reaches level 17. Conjuror/necromancer dungeons are good hunting grounds for that.

More info: http://www.uesp.net/wiki/Oblivion:Alchemy#Apparatus

Amelion Tomb is a part of the Amelion's Debt quest, a Fighter's Guild quest.

And for Alchemy equipment, I ran through The Temple of the Ancestor Moths dungeon. Looted all the chests, waited for the place to respawn and rinse n' repeat.