Welcome to UsingEnglish.com, andreawqh!
http://thesaurus.com/ Input a simple word, perhaps you can then find a complex word.
I am not a teacher.
Student or Learner
I kept having problems when I need to come up with a word that is more complex through writing. What type of writing method should i utilize through learning or what practice should I TAKE. THX
As MatthewWai suggested, using a thesaurus will help. However, it will not tell you if a suggested word is more "complex" than your original. Talking of which, what do you mean by "a more complex word"?
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.