You need to give more information. What are you trying to load? Do you have your VST folders set up properly? When you install a VST most will default to C:\program files\steinberg\vst . This is even if you don't own any Steinberg products. VST is a Steinberg technology.

In your track you should go to inserts, click or right click and a drop down menu should show allowing you to choose which plugin you want to load.