Usually googling "l[langage] tutorial" or "[language] hello world" would give you a lot of pages from where to start.
I know for sure that python and lua have documentation on their websites. This site also has a tutorial for C++.
Probably because it's the best way they could think of.
If you're learning using a book you can try another book, or look on the interent for something that explains them better.
What kind of things you don't understand?
Ops, I forgot to reply, sorry...
Not that it changes much. I learned that stuff mostly through googe and experience. Once in a while I found a page that explained something easily, or sometimes when programming I hit a problem and slowly working on it gave me more knowledge.
It took me months to figure out how python classes work and what a method is.
I can't really recommend a resource for all of that. The best advice I can think of is "code a lot". And if you're really stuck you can ask for clarification on some forum like this one.
The best I can say is to read your book from beginning to end and actually write the codes as you read.
Horton's C++ for beginners was a good starter-book for me.
You have to start with the basics and just continue to add to your knowledge from there. Generally everything is linked in some way or other. Variables hold information, arrays contain multiple variables, pointers point to the address of the variables, functions use variables and pointers to retrieve and modify that information, classes use functions and variables to achieve more advanced goals.
So start out at the ground and build upwards. As you read make sure to create a program that uses new concepts to ensure you know what the book's talking about. And finally, ask questions, be active in our beginner's forum, the people there are both learning and teaching at the same time, think of that forum as free tutoring sessions - they expect you to put some effort in but they will help point out where your code has problems.