Student or Learner
Should I use "of" or not?
"This seminar is focused exclusively on the feild "of" teaching English language."
Kite, note the correct spelling of "field". Remember our marvellous helpful phrase "I before E, except after C". There are a few exceptions to that rule but, in the main, it will help you with the spelling.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.