Good is a matter of relative perspective ... if you are willing to experiment, just create a character and enjoy.

Otherwise some pre-reading might help

http://deltiasgaming.com/

The best advice I can give is keep leveling. I have a fire Destro Staff Dark Elf Vampire Fire Mage, and I'm mainly focusing on leveling up all three of my DK trees (though Ardent Flame is my priority, due its abundance of fire DPS abilities), leveling up my Mages Guild skills, and leveling my Destro Staff. I wear mostly light armor for the magicka passives and use the Mage mundus stone for the max magicka increase. All of my attribute points are in magicka.

You can still make a DK Fire Mage even though you're a Nord and can't benefit from the fire damage passives of a Dark Elf. Nords actually make great Tanks with their passives, so you always have the option of having magicka Tank be your secondary role, if you so choose.

As for skills, you'll definitely want to have Inner Light (morph of Magelight, Mages Guild skill) toggled on all the time. Once you unlock the last skill in the Ardent Flame tree, Inferno, and its morphs, you can choose to replace Inner Light with that instead. However, for now, Inner Light is a must. Structured Entropy (morph of Entropy, Mages Guild skill) is also a great DPS skill that buffs your spell damage. The best DPS skills in the DK trees take a little while to unlock, so just keep working towards them. Once you unlock it, get Fiery Breath and morph it to Engulfing Flames to boost your fire damage. Lava Whip will likely find itself on your bar once you acquire it. For Destro staff, Destructive Reach (or Fire Reach, for a fire staff) is a nice DPS skill to use early on, especially with the fire knockback. Eventually, you'll want to get Force Shock and then Impulse.

Right now, your bar looks like the bar of a low level player working towards better skills--in other words, you're about where you should be. Your strength as a mage will increase with time. For now, make sure that you have at least one skill from each of your DK trees on your bar so that all trees level up fairly equally. This is key. Also, it's good to wear pieces of at least two of the three armor types you know you'll want leveled up for later. In your case, mostly light armor with a piece or two of heavy is a good idea. It might benefit you to become a Vampire for the opportunities it offers; it's not a must, but it's definitely something to consider. You could honestly get bitten as early as now if you want to start working on leveling it up; I've completed the associated vampire quest as low as level 12, so it's manageable.

I found several links you might to want to look at for more build specifics, or at least bookmark for later. Yes, most guides are geared towards endgame players, but that doesn't mean you can browse through them for info on what to start shooting for with your build. When you look at the links, simply ignore absolutely everything about "Champion Points", armor sets, potions, enchants, and other endgame jargon that doesn't apply to you; just skip to the skills and abilities (keep in mind that they're probably morphed names, so become familiar with what skills morph to what--the 'fextralife' wiki is good for that purpose) and the reasoning behind them, and read any other general tips present.


http://deltiasgaming.com/2014/11/30/shooting-star-eso-dragonknight-dps-build/

http://elderscrollsonline.wiki.fextralife.com/Dragonknight+Destruction+Staff+Survivable+DPS+Build

http://tamrielfoundry.com/topic/2-0pvp-one-shot-wonder-dk-build/

http://tamrielfoundry.com/topic/update-6-dk-dps-firespitter-2-0-magicka-first-version/

http://tamrielfoundry.com/topic/dkop-15-5k-sustained-dps-fire-mage-build-trial-vdsa/

http://forums.elderscrollsonline.com/en/discussion/171347/the-undying-inferno-dk-firemage-build


Good luck, and feel free to ask any other questions you may have. Hope that helps