In general you can select and format tables and cells just as you would in a normal word processor. However, there are a couple of differences. Also, you need to remember that tables in Help+Manual behave more like dynamic HTML tables than the static tables you may be used to if you have only worked with word processors up to now.
Changing the widths of table columns with the mouse always locks the width of both affected columns. Always use the Lock Column tool after changing widths to make columns dynamic again!
Table Properties (Reference)
How table sizing works (Reference)