Its left list show all currently loaded linear DNA sequences. Only the tagged sequences will be used for ligation. By default, all sequences with sticky ends are tagged. For blunt end ligations, sequences have to be selected manually.
The right list shows all products that can result from a ligation. "Poly-ligations" ("A-B-A-B-A-B-...") are not generated. For circular products, all logical products (e.g., "A-B" and "B-A") are shown; both are, in effect, identical, and only one of them should be tagged.
Through the "Ligate!" button, the tagged products in the right list are generated. Their names are created from the ligated sequences, and a description of the ligation is generated. Both names and descriptions may have to be edited manually afterwards.