You can progress your english writing skills by:
1. Learn to write atleast 5 new words every day.
2. Try to write on your own.
3. If you are fluent in english to speak, you might find it easy to write english. So, try to improve your speaking skills by reading newspapers, etc.
And the correction in your question is that the spelling of writing is not 'writting'. It is 'writing'. Double 't' comes in 'written'.
Hope that might help you.......^_^