Where to start with turtlebot?

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Hi, I start to learn ros and have the turtlebot. I did all tutorials and don't know how to go on. I have an assignment - turtlebot have to scan a figure from paper and after it must search the figure in the room, move to this figure and stop nearly.

As I understand, turtlebot have a ready base controller, navigation, odomentry and so on, I don't need creating it myself, in bringup minimal I saw this packages and used. But I don't understand how to use it separately, and I couldn't find their sources. Personally, I think to write node for global control, but also can't figure out what topics I need publish, subscribre, what services i need, what I must to write myself and what I can use ready-prepared?

I hope my questions is clear, if not asking please.