He taught me Autocad.

-> He taught me AutoCAD.

Its a computer program for constructing something.

-> It’s a computer program for constructing something.

He is older than me. But he is youger than other teachers.
-> He is older than me. But he is younger than other teachers.

He graduated Seoul national University.
And maybe he didnt go military service. Because he is so young to be a teacher.

-> And maybe he didn’t go military service it’s because he is so young to be a teacher.

He is tall. And he looks smart.
When i ask about that subject, he always answer quickly.

-> When I ask about that subject, he always answered quickly.

Of course he is a teacher of Autocad. So he can explain well.

-> Of course he is a teacher of AutoCAD. So he can explain well.

But you know, some teachers can't explain well even though they aleady know about that question's answer.

-> But you know, some teachers can't explain well even though they already know about that question's answer.

I think he is study more than others.
When he gave a project to draw Gundam : it's a robot in animation in Japan, using Autocad I hated him. Because it was too difficult to draw.
-> When he gave a project to draw Gundam: it's a robot in animation in Japan, using AutoCAD I hated him because it was too difficult to draw.

But we did. And we can use Autocad well now.

-> But we did and we can use AutoCAD well now.

I really appreciate him now.