Bethesda Softworks started a beta for Fallout 4‘s Creation Kit on PC but a lot of people may not have gotten in. The good news is there’s still a way.
If you head to the forums, you’ll find instructions from the developer to head here to sign up (which includes non-disclosure agreement) and then replying to the post in question with “YES”.
As of now, we only know that the Creation Kit will be releasing for PC players sometime this month. When that’s going to happen still remains to be seen. As for mods coming to consoles, that will take a bit longer (especially since they’ll arrive on Xbox One first and then PS4).
The next DLC for Fallout 4, Wasteland Workshop, is out on April 12th for Xbox One, PS4 and PC. The more significant DLC expansion Far Harbor is out in May so stay tuned for more details on that front.