You are now the owner of a few Hero Souls. Each soul gives you +10% DPS to all of your heroes (adds it to your base) and makes progressing back up to where you were, and higher, much quicker.
You will also have the Ancients tab open. You shouldn't worry about those on your first Ascension. As you may have guessed you will be doing this many, many times.
Progress through the game once more, meet new stronger heroes, and when the monsters seem too beefy to continue ascend again. It is suggested to only ascend if you will get at least 150% of the HS you got last run, or 50% more. If you can make that number even bigger, all the better!
It will start to get difficult to keep up with what was mentioned above, seeing as Frostleaf is hard to level and Dread Knight is miles away. This is where you go back to Treebeast, as weird as it seems, and level him to 1000 or 1025. This will put his DPS to that of or greater than Frostleaf's. You will then work your way down the heroes again, leveling most of them to 1000 as the previous ones become obsolete to level. The heroes to not level to 1000 would be: Betty, (Leon is optional) Broyle, Midas, Amenhotep, Grant (doesn't compare to FL generally, especially if there are a few gilds on FL).
Go through this process until you have accumulated around 60 HS, at which point you should invest in the Ancients tab and summon Vaagur, Ancient of Impatience. (If it isn't there, don't spend too many hero souls re-rolling)This will lower the cooldown of all of your abilities by up to 75% when fully upgraded (costs 45 HS from purchase to maxed out).
Continue to ascend with ever increasing HS values until you have a few hundred. This is where you get to start choosing your path to go on.