i know how to use surface features , but i dont know : how to think right to make surfaces i need.
Welcome to the forum
Although you know how to use the features, have you considered doing more tutorials so that you get a better understanding of workflow practices. Also, perhaps see if there are any recommended books on the subject that may help your mind process on this.
A lot of this could also just come from practice and learning from mistakes.
Google - Allen Iverson "Practice" interview
The first step is to get a pencil and paper and do the best sketch of your design intent that you can generate.
The second step is to post image of that sketch here.
The third step is to attach the *.sldprt file of what you have attempted so far in an effort to achieve your design intent.
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