And please, for goodness sake, start with the basic tutorials as well as learning otehr basic stuff. There is absolutely no point in diving into a tutorial that uses a complex effect like Shatter, if you have no clue about some fundmantal things (no offense).
You asked for tutorials, and Mylenium made the good suggestion to begin at the beginning. Here's a page that gives a good collection of tutorials and other resources for getting started with After Effects:
After Effects is not a video editor and AE behaves like almost no other application you have ever used because it is like no other application you have ever used. RAM previews are temporary files, completely ephemeral. If you modify anything, even slightly, the stored preview becomes obsolete and must be redrawn from the in point to the out point. It doesn't take long to understand why this is happening but it never really becomes acceptable so you learn, after hundreds of projects, to use low rez RAM previews, to save RAM previews to disk as movies, to use lower frame rates, to turn off certain features like Motion Blur, and dozens of other time savers and preview savers.
The single most important first step in learning After Effects is forgetting almost everything you know about Photoshop and Premiere. After that, patience. There are those of us here who have been using AE for more than 10 years and we learn something new every day.
Sounds like you are using the space bar instead of the proper "0"key on the num pad.