Help for a beginner on placing timing marks

I press V to select the Event tool, then move the mouse to the correct spot and click.  That will place the timing mark.  Then if you want to fine tune, move the cursor until it turns into horizontal arrows - you can then drag the timing event left and right.

Be sure to experiment with using the split feature.  Let's say you want to place timing marks on every beat.  Place one, then place another several seconds later.  Then split that region into X cells.  A lot faster than placing each one individually.

For example, I wanted to do a chase down the street - I had 73 mini trees.  Instead of placing 73 marks, I placed a mark at the beginning and the end.   Then I split that cell into 73 cells.