You can find information about the concepts, but you would be wrong to think that wikipedia or google will solve your homework for you. Practice problems are much more specific than “real life” problems. In other words:
applies to online resources as well. You are meant to be able to figure things out for yourself.
Nothing wrong with homework problems from the book - that’s usually easier because the textbook has examples directly related to the homework. You should be able to take good notes that let you recall important lecture concepts.
It really seems like your problem is that you just didn’t develop the proper study skills of a high achieving student. It’s a bit late now and you might just have to grind through it and just finish your education the best you can. One year to go and then you will be finished with it, so it’s not too bad.