is there a way to organizate my vst ? and a way to use more vst?

A Bus is a way of grouping multiple tracks together for occasions where you want to apply the same effect on several different tracks.

You set this up on the Edit Panel at the left end of each track in your multrack session--it's the drop down box with the left facing arrow.  It'll almost certainly be set to Master by default.  Click on that and it will offer "Bus" as one of the options.  The first time you do it, you'll be offered the option of "Create New Bus".  After that, you can select the bus you have created already or make another bus.

The result of this will be another "Track" down at the bottom of your session which gives you control of any tracks added to that bus.  If you want them all to have the same effects, just add it to the bus and the effect will be applied there rather than to individual tracks.

A bus is also useful in the mix by allowing you to group related tracks together.  For example, if you have 8 tracks of backing vocals, you can set the balance the normal way then control the balance between lead and backing vocals just by adjusting the level on the bus.