пожалуйста, помогите мне

привет all,
I consider myself a beginner in Russian and have had a fairly easy time with the grammar, and similar experience with pronunciation. I can pretty much see any word in Cyrillic and say it correctly now(according to the Google microphone, that is) just from reading it. However, a stumbling block for me has been the sounds of the "o" and "a" distinguished when I write. Sometimes I hear the "o" said very o-like (for example the word for progress), and it is easy to write words containing this sound. Other times, I write a word out with an "a" like it is said and find that it should have been an "o."Can someone please help me with this?
спасибо
лаура (Laura)

Привет, Лаура!

This is one of those tricky things that sometimes pops up when studying languages.
Please check out lesson 1.6 "Learning to Read in Russian" included in the "Language and Culture Lessons"  where there is an explanation of when "O" is most likely to be pronounced "A."  Basically, it is just a matter of where the stress falls in a word and there is no option other than learning which word is spelt in which particular way. Hope this helps. 
Удачи,
Наталья

Spacibo, Natalya!