hi, i'm a newbie in the forum and in the Russian. My question is:

I'm Turkish, and in my language, i say "o" letter as usual ( like "orange" or "hole"). But i realized that in Russian, you pronounce the letter "o" as "a" (пока) , and sometimes you pronounce like "o" (добро)

i heard that its about stressing, but how can i know when i will stress which letter? like i said before, i always say it like "office" as though it is in french.

i'll be glad if you can help me