First time opportunity to give a seminar Recently I had a talk about the topic of my master thesis with the professor I currently work for (he wasn't involved in the thesis). I mentioned that there are interesting results and that I would like to present them, if he'd agree. He proposed to not only give a presentation but a seminar.

I've just graduated from my Master's and never given any lecture, course or seminar before. I would be happy to take this opportunity as I enjoy teaching and I expect a good experience.

If I'm willing to do it the professor expects a scheme of the seminar and that's the point where I am stuck. For how long of a seminar time should I aim for? Introductory or deep into the matter? What exactly is the difference between a seminar and merely presenting my thesis again? In my understanding seminars include practical approaches. Should I focus more on practical issues or my own work?

The subject is quite technical in detail but this is not very obvious from the topic alone. I expect students to may have heard of the methodology but never employed it themselves.

I'm quite lost on how to tackle this task though excited to have this opportunity. I realise that my question isn't really well fleshed out but I'm happy to hear opinions nevertheless.
If you have presented your thesis before, the seminar could be something similar to it. However, a seminar is usually given to a wider range of audience, and thus you need to make it more accessible for someone in the audience who may not be familiar with the subject. Aim for an accessible introduction, and save the technical details to the second half of the talk.

As for how long the seminar should be, you need to ask the professor how much time you have to talk, and how much time you have for questions and answers.