I'd crack open my Biology book or A&P book, or do a google search.
Ah, sorry lol...didn't understand what he was asking.
For morula...I just think of a soccer ball, just a bunch of cells packed into a cell. Blastula think of shooting a hole straight through the center...since the center is hollow, and then the gastrula is when the cell kind of folds in on itself, making three layers.