Each form has 10 multiple choice questions. If you can get high marks on these without guessing or looking at answers first you are well on course for a grade 7, 8 or 9. Topic 1 is the most important for improving your grade as the content in this topic is tested on both paper 1 and 2.
Every google form has links to you tube videos where the theory is explained. If stuck do watch these as the idea is always to fix gaps in knowledge and understanding. If nothing else they should show you where to look for help in your workbooks. At the end, if you have answers wrong there is feedback as to where you have gone wrong.. Again, pay really close attention to this as all the questions are very similar to exam questions and the aim is always to improve.