You can choose from 3 topics. The 3 topics are
Writing Skills
Grammar
Business Communication
Click on a topic and choose a subtopic to work through a tutorial and activities.
from GCFL
These are exercises to practice writing. They are mostly free writing - you just write what you want about the topic for as long as you can without worrying about spelling or grammar. The idea is to get your ideas flowing.
This a writing textbook you can read online. There is a lot of information and some activities you can try and see the correct answer.
English Vocabulary and English Grammar
There are no tutorials on this site. It is a good place to practice but not as good for learning new things. Click on the three lines in the top left corner. Choose Categories and scroll down to see English and choose English Vocabulary or English Grammar.