Change the sentence.
Having done this, he went away. (Complex Sentence)

• Simple Sentence to Complex Sentence: (Having + Verb এর past participle form যুক্ত)
• Structure: Having এর পরিবর্তে When বসে + Subject + had + Verb এর past participle form + বাকী অংশ।

- Simple: Having done this, he went away.
- Complex: When he had done this he went away.
- এ বাক্যে প্রথমেই Having এর পরিবর্তে When বসেছে।
- তারপর Subject - he বসেছে।
- এরপর had + Verb এর past participle form - done বসেছে।
- বাকী অংশ অপরিবর্তিত রয়েছে।

• এ জাতীয় আরোও একটি উদাহরণ - 
- Simple: Having told this, he went away.
- Complex: When he had told he went away.

Source: Advanced Learners Communicative English Grammer & Composition By Chowdhury & Hossain.