Hey Hashim, sometimes you can create pseudo selectors that target individual HTML elements that don’t have any uniquely defining ids or classes, e.g. nth-of-type. And the next iteration of Microthemer’s selector wizard will include these.
But sometimes, even nth-of-type doesn’t target just one element. And so you would need to insert an id or class via WordPress’ content editor (on the Text tab), assuming that’s where you wrote the paragraph in question.