Hi Rolf,
You can have up to 5 columns in a section, you can change the number of columns in a section by clicking the numbers along the top of a section(|1 | 2 | 3 | 4 | 5 |). You can't adjust the width of a column but you can adjust the width of a section by clicking Edit on the section header. If you are refering to columns in a grid if you click on Edit on the grid object and go to Step 2 you can add, remove and change the size of grid columns here.
-Michael