Im at the beginning of the game and I have serious problems with opening any doors. The doors I´m talking about are the one that needs a statuette or figure and the doors that doesnt have any conventional locks and warded against simple spells.

OK. For a bunch of those doors, you need to activate the sewage golem, using the activation stone you find in the room with the guy in the tank. There is one more warded door, but you can't get to the air elemental statue for opening that door until you activate the golem and tell it to open the doors.