Hi Kristaline, and welcome to the forums. Congratulations on your incoming KS2!
Regarding manual mode, the best advice I can give is to learn about exposure. This is essential to shooting in manual mode, but will help with all other modes and your photography in general.
All of the information you need is available by Googling "
how to shoot manual with DSLR"... however, I recommend you buy a decent book on the subject. One of the best (and I own a copy myself) is
"Understanding Exposure, Fourth Edition: How to Shoot Great Photographs with Any Camera" (I've linked to Amazon Canada here for your convenience). If you read, learn and practice the straightforward teachings in this easy-to-read book, you'll be all set. It covers everything you need to know, without having to trawl through multiple websites, asking various folks for advice that might be inaccurate or conflicting. Save yourself the trouble, read this book and put what it teaches into practice. You'll do just fine