Investing 10-15 points in Health by the time you reach lvl 50 is a decent number if you're worried about squishiness. Though you are an Imperial, so you might be able to get away with less. Ideally, you want as many points in Stamina as possible to maximize your DPS; you actually don't have to put any into Health if you feel you can manage. If you're a stamina build, don't bother with spending any points in Magicka. Wearing 5-7 pieces of medium armor and purchasing the medium armor passives will also help significantly with your stamina. Here's a few links to some stamina DK builds you can check out for more info:

http://deltiasgaming.com/2015/03/08/the-bloody-butcher-dragonknight-dps-build-for-update-six/

http://forums.elderscrollsonline.com/en/discussion/198909/stamina-dk-dps-for-group-pve-dual-wield

http://esoacademy.com/builds/2hdw-dk/

Keep in mind that these builds (and most builds in general) are geared towards high level players. Simply ignore everything that doesn't apply to you right now (Champion Points, Armor Sets, Vet Dungeon set-ups, etc.) and skip to the skills and general tips sections for advice.

As a stamina DK, you're mainly going to be relying on your weapon abilities. Steel Tornado (morph of Whirlwind) and Rapid Strikes (morph of Flurry) are your go-to DW skills. Some DK skills you might pick up are Burning Breath (morph of Fiery Breath), Green Dragon Blood (morph of Dragon Blood), Unstable Flame (morph of Searing Strike), and Flames of Oblivion (morph of Inferno). Feel free to experiment with different skills and rotations to see what works best for you.

Hope that helps