The Effects tab is located in the Project panel, beside the Media Browser tab. Click on this and a menu of effects, each of which has sub-effects, appears. At the same time a panel opens up in the Source monitor, (just above), called Effects Controls.
In order to apply an effect choose the sequence in the Timeline where you want it to appear by moving the playhead over the thumbnail visible in the video track. Choose an effect from the drop down menu and drag it to the playhead. Click on the clip thumbnail to select, then go to the Effects Control panel at the upper left of workspace, scroll down until you find the applied effect, and when you click it you will see all sorts of variations, as well as numerical values for fine tuning. If you make changes here you will see them applied in the Program monitor to help you design your edit.
To remove an effect click in the Timeline at the clip with the effect then go to the effect name in the Effects control panel. Click on the FX icon to the left of the name and a slash will appear across it and the effect disappears from the Program monitor.