Remember that once you accept this ambition, you can't choose another one until it is achieved or you die. Since you’re in Norway, lets put that ambition on. This has some limitations such as invasion CBs only being available to that de jure kingdom and neighbouring lands but that's still better than having to fabricate claims on all those duchies before being able to create the kingdom. Now pagans with the ambition "Found the Kingdom of X" gain unlimited invasion CBs until that goal is achieved. So with the offspring issue now solved you can wait for those to appear and begin taking over your immediate area. I recommend finding someone with attributes like genius, quick or stats like high intrigue, these will make your heirs have generally positive traits that are transferable over many generations and having good intrigue means that she can possibly become your spymaster and you can easily assassinate your sons if there are too many for your territories. Your guy isn't married so let's get that started. You have a bit of cash but if you want more the first thing you need to do is start conquering or raiding. When beginning as the Ylving you can see that you have 4 provinces and you can field around 1000 levies.