Merhaba, I have a problem with the word OTURMAK.

it means to sit but I think there is another sens ! Because When you tell someone : what are you doing ? Often people say : ben oturmak, but for me it means nothing !!!!

teşekkür ederim yardim için ! 

hope you mean that :

X: hey, what are you doing?/ Merhaba, ne yapıyorsun?

Y: i am sitting./ Oturuyorum

When s/he told shortly "i am sitting" as an answer to this question s/he actually means that "i am not doing anything other than sitting emptily" additionally, people usually use "hiç" before "oturuyorum". like that:

X: Merhaba, ne yapıyorsun?

Y: Hiiiiiç. Oturuyorum.