Greetings,
I've read Silas Marner, but it was many years ago.
If you need to comment on the language used to present him, that gives you plenty of scope since the whole book is about him.
Looking at the adjectives used might be a place to start - how is he described? He's a simple, private person I seem to recall. Look at how he changes when the baby turns up. How does the author show the change in his personality?
You should use quotes from the text to back up what you say. That doesn't mean your whole essay should consist of nothing but quotes, because your teacher wants to hear your own ideas, but you should back them up with quotes whenever possible.
Hope that helps.
Peace