how do i know what board i did or where i left off?

ok so is there a way to tell if or where i left off while campaigning ?  i tried to go to harder boards but it just wont let me it tells me to finish the quest . i have done all the dailies and the monthly so what do i need to do ? start from beginning. again and go do every board? i cant get any gear unless i do the onslaught map and then i can only do like the first set of 3 waves. i really dont want to start from the beginning again

You should have a campaign quest line. Once you finish betsy campaign it unlocks freeplay and of course onslaught and maybe incursion, but I don't recall. Anyways, at this point, you are bound to these playset and can't go into any end-game related content or "boards" as you called them until you have achieved level 50 on at least one hero. You're unfortunately stuck leveling in the freeplay maps which of course limits you on gear, however you do get a lot more experience than you would if you tried to level playing end-game content. 

Press "J" on your keyboard to see the quest log. You should have somewhere that says: COmplete map X, or Talk to character X or Get to level X.

Do that and move on to the next quest afterwards.