Well, I’ve hit a roadblock or mental block as far as my dress goes.  I’ve got the biggest part of the bodice done but one of the last steps I really don’t understand so my almost-done bodice has been hanging on the backdoor for almost a week. 

Here’s the dress as it is now:


Here is the step that has me bumfuzzled:

And the accompanying diagram:

I don’t get the last part about gathering the bodice.  I don’t know how to gather.  Any thoughts, suggestions, instructions, tips, tricks?