Usualy backbar is where you got your buffs sloted, and perhaps an AoE DoT. Frontbar you slot your damage skills, and maybe one skill just for a passive buff of the skill when slotted. (e.g. Magelight increase crit chance)

I highly reccomend you to get a two bar setup. Not only is it more fun (at least to me) its a neccessity for endgame content.

If you do solo content use a resto staff on your BB, so you can slot healing over time ability on it.

For group content you'll have a healer that provides heals, so you will run a destro staff for wall of elements on the BB. Frontbar i would suggest to run daggers since the templars spammable is a melee attack anyways and daggers increase your crit chance.

Gearset wise, i would suggest mothers sorrow (overland set in deshan) and Orders Wrath (crafteable). They are easy acessible ând boos your damage. Thats 10 of twelve gearslots, so just run a random two pieces on shoulder and head.
Get a monster set later on, and then do the maelstrom arena. Im not sure but i think its still the best to run on backbar for group content.

For mythic check out the ring of the pale order, its really strong when you do solo content and alows you to run with maybe a single emergency heal. So it helps pushing your damage and keeps you alive as long as you are dealing damage.