(Attock VU Group) Project Trouble

Hello Friends and Sisters,
My third Deleverabe lis still stuck as I am stuck in Sequence Diagrams.
Instructor has commented in my deliverable that "Provide a sequence diagram for each of the use case (usage scenario) from SRS document". How do I use use cases in sequence diagram as far as I can Understand I will name the boxes as Use Cases??
and I have mentioned four actors in SRS so Do I have to draw 4 separate diagrams for these actors and show their use case in it or I have to draw 1 sequence diagram and show entire system in it. My Project is SEO any one can replay specially SEo waley

Please Please Help me give me some suggestion about this Dragon grams Please

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