Dear Victoria,
You’re on the right track, but it looks like you got the syntax a bit wrong. To create a particle you need to write something like
Particles::Particle<dim> particle;
You’ll note that the specific constructor that is called is inferred from the arguments given to the instance of the class that’s being created (in this case, no arguments —> default constructor).
There is a new tutorial, namely
step-70, that uses particles. I don’t know whether or not it’s pitched at the right level for you to get to grips with some of the fundamentals (at first glance, it seems to involve a number of more advanced techniques). If it’s not quite tractable for you, then you could also take a look at some of the
particle tests in the test suite, such as
this one, that might provide snippets of information that you need as you build up your understanding of this particular feature of the library.
I hope that helps you a bit.
Best,
Jean-Paul