Correction:  Student's sentence   Corrected sentence        Grammar explanation       Better sentence            

I live in Busan, so I don't have many opportunities to go to Seoul.

This sentence is correct. 

So when I go to Seoul to Field Trip, I'll be excited. 

So when I go to Seoul for a field trip, I'll be excited. 

to - for 

please be mindful of the proper use of capital letters. Field trip is not a proper noun.

This is because I can see, feel, and experience things that are not in Busan in Seoul.

This sentence is correct. 

If I have a chance to go to Seoul again, I really want to go to Everland and Lotte World in Seoul!!

This sentence is correct.