1. step
From the menu [File] you may select which type of cell you would like to create, namely [new: new asymmetric cell] or [new: new full unit cell] or [new: new cartesian cell] .
2. step
an editor opens and you may make your entries
3. step
save the modified file by changing its filename "cell/new" to "cell/yourfilename"
4. step
select [File][open cell] to load your newly created file