I have wasted 3 hours to understand the correct steps to create a cell.
In AutoCAD is really more easy and clear. The command: Block opens a dialoog with the necessary buttons: to put the block's name, to select the entities, to pick the origin, etc...
In the case of MicroStation, it would be interesting a button called "Create cell" in the ribbon which opens a similar dialog.
Obviously, it is needed a current Cell Library to do it, so this would be also a request.
Dialog from "Create Cell" button:
1) Attach file for Cell Library.
2) Cell's name.
3) Description cell.
4) Cell type.
5) Select elements.
6) Define Cell Origin.
For the traditional workflow:
Attach cell library (or create new)
Define cell origin
Select elements
Click "create cell"
Enter Name, (optionally) description, select type and hit Enter
should be "create design model"
Much better workflow:
Open Cell Library in MicroStation (not attach)
Create a new Drawing Model and give it a proper nae ( = cell name)
Create content