create the layout with portlets in it
1_column - gives you a single column layout
2_columns_i - gives you two columns split 50/50
2_columns_ii - gives you two columns split 30/70
2_columns_iii - gives you two columns split 70/30
3_columns - gives you three columns
1_2_columns_i - gives you one top initial row, followed by 2 columns split 30/70
1_2_columns_ii - gives you one top initial row, followed by 2 columns split 70/30
1_2_1_columns - gives you one top initial row, followed by a row with 2 columns 50/50 split, followed by another row
2_2_columns - gives you one row with 2 columns 70/30 split followed by another row with 2 columns 30/70 split.