There are a couple different ways to make multiple cursors in Atom. The first way is to use the "Find and Replace" function. To do this, open the "Find and Replace" panel (Ctrl+F or cmd+F on a Mac), and then click the "Replace All" button. This will create a new cursor at each instance of the search term.
The second way to create multiple cursors is to use the "Split Selection into Lines" command. To do this, select the text you want to edit, and then press Alt+Shift+L (or cmd+Shift+L on a Mac). This will create a new cursor at the beginning of each line.
