Noob TankingFollow

Examine all of your spells and read the descriptions. You are looking for spells that increase hate or threat. SKs are not hugely endowed with taunts, and at level 16 you probably haven't started all of your spell lines yet either. Taunts need boosting within your AAs as you earn them, if your prime concern is tanking.

The lines you have, or will have soon (according to ZAM list) are:
Insidious Whisper
Blasphemy
Innoruuk's Caress
Hateful Slam (requires shield?)
Grave Sacrament

... which will do you for now. There are some other new spell lines that come in after level 60 or so.

Watch out for the colour coding of the spells. Icons with blue backgrounds are AOE (area of effect) and will ensure that any creature within range will then try to chew your face off. Green backgrounds only affect the current mob (all the members targeted). SKs have quite a few AOE spells, so it's worth arranging your hot bars so you don't hit them by accident (as that's a very quick way to wipe a group - yes, I have the T shirt).

If memory serves, your taunts will be the icons that flash for the second stage of an Heroic Opportunity most of the time.

If you're new to tanking this may also come as a surprise to you but as a tank, your main job is not to dish out damage to the mob, it is to absorb damage from the mob.

As such, your focus will always be on keeping the mob from dealing out damage to the members of your group who are wearing tissue paper armor...

Correct. This ability changed with GU57, prior to that you did need to have a shield equipped to use it.

Pretty much everything has been said to get you started. Later levels you should have enough STA that you can focus more on STR (since that is what will increase your power pool).

Look for gear that says "+number ability mod" as this will increase your taunts, as well as your other attacks/abilities.

Mitigation and resists! If you plan on tanking heavy duty group or raid zones those will help just as much (if not more) than having a lot of hp, since this will help reduce the overall damage that you take.

QFT. To add, keep your threat and heal abilities above par too. EG Hateful Slam. Try to aim for Adept for your self heals for sure, and threat if you plan to tank a lot.