Page History
...
To set a breakpoint, put the cursor on a statement, use the Toggle Breakpoint command in the ribbon or right-click and choose Set As Breakpoint from the context menu. You can also press the F9 key. Only lines with executable commands may have breakpoints. For example, you cannot set a breakpoint on a comment line or GROUP_BY command.
You can open other objects for editing during the debug session and set breakpoints where required.
...
To continue debugging, either use the Continue Execution command (F5), or use the Step Into (F8) and Step Over (Shift + F8) commands to move forward one statement at a time.
To disable or remove breakpoints, use the Toggle Breakpoint command or the Breakpoints Toolbar in the 6.2.1 Breakpoints tab.