If you need to see the line number you are on, look at the lower right corner in the status bar. It will say something like "Ln 73, Col 12" meaning the cursor is on line 73 at position 12 of the line.
If you want to jump to a particular line, you can hit Ctrl-G, make sure Line is selected on the left, enter the line number on the right, and hit enter.
If you get compiler errors or warnings that mention a specific line, you can just double click on that error or warning in the output window and the file will come up with the cursor on the appropriate line.