The Anbu
 

ok so how strong are the anbu really, and how can u become one, i remember the anbu getting defeated so easily and being very stupid eventho they are supposed to be like one of the secret ninja forces in the village, and wat class are anbus?? they dont seem to be as strong as some jounins but at least as powerful as a chuunin, they seem a bit overated tho, esp when the tsunade, went like this is only a normal class mission, not an anbu one, to the new leader guy.

The ANBU, meaning "dark side" is actually short for Ansatsu Senjutsu Tokushu Butai (literally Assassination Tactics Special Military Force). The ANBU work directly under the leadership of the Hokage. This specialized ninja battalion generally work in groups of four to five. They are responsible for assassinations and missions requiring highly trained ninjas.
You don't need to be a Chuunin, Jounin, or whatever. It's just a name.
If you wanna be an ANBU, it depends on how strong you are. Like Itachi became one at the age of 13. It isn't even known if Itachi became an official Jounin before wiping out his clan.
The ANBU come to the ninja, and ask to join their organization. It's basically like Special Ops, and they're just a special part of the Ninja force.

then the anbu seriously needs to ask some better ninjas, i mean some of the anbu got owned by a dagger, like when they were in the forest near the hidden village of rain and the traitor guy stole the sword.

Well, ANBU aren't neccessarily those who are exceptionally strong. the ANBU is an assassination team, sent out to kill certain people. They are also used to help fight in battles, like when the Sand and Sound inflitrated Konoha.