What must I choose?

Hello everybody! Hi Alan and Torsten! I often read topics in this forum. I must admit, this forum helps me to understand many english words and expressions.
Sometimes I write letters in English to my friends. As for me, English is a very rich language with nice pronunciation. I have many doubts. Which word must I choice.
I write: You say rightly, you think rightly
Perhaps I must write: You say properly, you think properly
Probably, I can use word correctly
What do you think about it?
Many thanks

Dear Zulfiya,

As you know there are so many different ways of expressing an idea and often the differences in meaning are very subtle. Regarding your question I think it really depends on what exactly you want to say. So, the more context you provide the better the chances to select the appropriate words.[YSaerTTEW443543]

TOEIC listening, photographs: Ancient ruins[YSaerTTEW443543]

Dear Torsten, I understand it.
For instance, I want to say to friend : You understand this phenomenon( phenomenon in nature). What must I say?
You think rightly or you think properly?
In my performance, these words rightly and propely are a bit different. But I don’t know this difference.

‘you understand this properly’ means that someone understands something correctly.[YSaerTTEW443543]

TOEIC listening, photographs: An open air market[YSaerTTEW443543]

Dear Torsten, you helped me to clear this interesting situation .
Thanks . Zulfiya