I want to join the MTP program... but it seems i can´t...

Is it closed or what is it? When can i try to join?

It's in a closed state at the moment (the phase has been on for a month.); They will soon announce the next phase at which point you can put in your application

There's a link to subscribe to a forum, including the general "MTP" forum that you're reading right now. From there you can choose to be emailed a digest of new posts each day, which should work just fine to alert you when another MTP phase is beginning.

Here is that link, in case it's not clear where to find it.

The new phase application will probably be started somewhere in November, each phase lasts 3 months, and the current one started in the beginning of September.

First MTP phase is on its way for 1 month now. One phase will last for 3 months in total. I suppose that then new applications will begin...