If you want to use someone else’s work, you can generally only use it if:
You should always read the words of the copyright notice so that you know how you are allowed to use the work.
A copyright owner might say that you can use their work in any non-commercial way. This means you can use it as long as you are not making any money out of it. For example, you would be able to use this work in a school website competition.
Sometimes a copyright owner will say that you can use their work for free, but only for personal or domestic use, so in this case you wouldn’t be able to use this work in a website competition.
Some copyright owners make their work available for free, for example under Creative Commons.
If you are copying the work as part of your homework or for a class assignment, you often won’t need to get permission, but if you want to use the work in other ways, such as entering the work into a competition or exhibiting your work publicly (such as, on the internet), you will need to get permission from the copyright owner.
You can only change a work (for example, alter the colours of a painting, crop a photograph or edit an article), if you have permission from the creator and/or copyright owner to change it.