Functional Grammar, clause, theme, metafunction

I'm currently studying functional grammar and It seems that I am not able to get a clear concept of it.

1. e.g. "The venue is arranged after an introductory display of art featuring the sculpture, which is made by a famous artist."
Can "after" and "before" be the textual theme of a clause?
I know that "which is made by a famous artist" can be regarded as clause but can I say the topical theme is omited in this sentence in functional grammar field?

2. "With the assistance of the tutor, I am able to finish the assignment now."
Is "with the assistance of the tutor" the topical theme of the text?

3. "You should finish the work by 10pm." & "Peter, please give me a book."
Which words are considered as the interpersonal theme?Are they "You" and "Peter"?
or how can I interpret this sentence?

There are countless question that I would like to ask lol. It would be grateful if you guys can illustrate the answer by giving more examples.
Thanks for your kind attention to my post><.