Before I answer your query, let me correct first the grammar of your question, thank you.
When can I use the words "probably" and "possibly".
Perhaps they have similar functions:
Possibly suggests something that is possible or may be realized
For example: A new park to include a pond and possibly a playground.
Probable suggests likely or to be expected.
For example : I'll probably come tonight.
I hope this would help you in choosing the best answer, thank you