If yoyu look at the png above , at the very top of the picture is a red line, that is the timing mark.
If you dont have nay then this is quick way to to do so
Select a sequence first.
Click on Settings-> click Sequence settings-> Timings tab.
Click on new (at bottom of box), this opens up to a dialog box called New Timings,
select 50ms and press ok,
timing mraks will appear on the worksheet area of XL4 and you can select "Cells" to add effects.
If you install Vamp plugins they will found in the same spot, instead of selecting 50ms, the list of plugins will show up and away you go.
Cheers Boof63