This page is designed to help you learn Alchemy in Skyrim.
For each ingredient you have, if you look at it in your inventory, it'll show you 4 possible effects - all initially unknown. To level up your Alchemy you need to learn all 4 effects for all the ingredients.
Suppose you have some Garlic, and you only know the first effect (which you can learn by eating it). Open this page, and look for 'Garlic' in the table. You can see that the second effect is 'Fortify Stamina'. Select this in the table above, and all the ingredients that don't have the 'Fortify Stamina' effect will vanish. See which of the remaining items you have in your inventory. For instance, you might have some Lavender. Brew a potion with Garlic and Lavender, and the 'Fortify Stamina' effect will be discovered for both.
Skyrim lets you brew 3 ingredients into each potion, so if you select another effect (say the "Regenerate Magicka" one), that will also show you ingredients that have that. Thus, if I happened to have some Dwarven Oil in inventory, I could add that to the Garlic and Lavender and learn 2 effects at once.
This page is based upon data from the "Skyrim:Ingredients" article on the Unofficial Elder Scrolls Pages (uesp) and is licensed under the Creative Commons Attribution-Share Alike License.