I constantly hear this but I have no idea how to do it. Clicking it will drink poison so :facepalm: Im lost, please help. Thanks.

Fistly, you don't technically poison your arrows. You actually poison the next shot from your bow :grad:

If clicking the "poison" causes you to drink it then it is not a poison.

Poisons come in green bottles and can only have negative effects. If you have a mix of positive and negative effects then you get a potion.

So, I click the poison and the affect is added to my bow? If so, where do I get said poisons.

Either (most likely) you will make one using your Alchemy skill, buy them from alchemy and some general stores or find them scattered about the game.

Meh, it feels a bit off in the RP sense for my stealthy assassin to make potions but, ill come up with some weird story in my mind of why he would do so. Perhaps his mother owned a flower shop so he likes to pick flowers..... (every man is a mamas boy deep down, no matter how many thefts or murders he committed). Hmm, yes that leaves me satisfied.

It really wouldn't be hard to incorporate alchemy into an assassin's character. I've used it for all of mine, just because poisons are essential tools of the trade. If you want to RP accordingly, don't make any potions, just poisons. Eschew restore fatigue and health potions for drain fatigue and health potions. If you can find a drain speed or paralyse combination, more's the better. Alchemy might concern itself with flowers, but Nightshade, Stinkhorns and Wisp Stalks too.

Alternately, you might want to check out Shady Sam. Go behind the Handy Chestnut Stables at the Imperial City, and follow the walls to the left (if you're facing the Talos Plaza door, when you've come over the bridge). He'll be standing behind a buttress, selling all kinds of evil or illegal produce.

Not quite.When you click on a poison you will be asked which weapon you want to apply the poison to,select that weapon and your bow or sword will now have a poison affect added to it.

Note that when you poison youre bow only youre next shot will be poisoned,if you miss you waisted a good poison.
When poisoning a sword or blunt weapon you can swing as many times as it takes to hit something.

Also the poisons you make youreself will be much more powerfull than any poison you can buy.

Is it possible by the way to PREPARE arrows..
it svcks to have to poison arrows as you shoot them (only your next shot)
can you just poison 100 arrows?

No. It is possible however to improve things somewhat by hotkeying a stack of poisons to streamline the process. Bear in mind that you can only have four poisons active on one foe at a time.