Best way to learn anatomy imo is simply drawing from life, can be nude art classes or going around drawing people you see in cafes, parks, trains, etc. If you can't do this for one reason or another, there are also plenty of sites with nude models, or clothed if it's more comfortable but nude gives you a better idea of the form
Another way to learn is to trace over images and break down the shapes, learn about the volume and how everything is put together. The more diverse the bodytypes the better.
As for actual tutorials
this video by Ethan Becker really helped me personally break down shapes a lot better in highschool. He has quite a lot of interesting art tips so i recommend taking a look at his youtube in general!
Most importantly, DO NOT GET HUNG UP ON DETAILS! The more you focus on details, the more you end up losing focus on the overall image and practice. To negate this, i reccomend using a medium you can't erase.
Here's some of my own stuff i've done last year, talking about this makes me realize i should get back into it LMAO oopsies o.o