To align text within table cells just use the CSS text-align:<left|center|right>; display:block; commands. These commands can be combined with other CSS commands. The block forces the display of the span to 100% width of the containing element.

Important: Don't forget to leave a space between trailing %% and |.

This

||%%(text-align:left;display:block;)Left Heading%% ||%%(text-align:center;display:block;)Center Heading%% ||%%(text-align:right;display:block;)Right Heading%%
|%%(text-align:left;display:block;)Left Cell 11%% |%%(text-align:center;display:block;)Center Cell 12%% |%%(text-align:right;display:block;)Right Cell 13%%
|%%(text-align:left;display:block;)Left Cell 21%% |%%(text-align:center;display:block;)Center Cell 22 (longer for illustration)%% |%%(text-align:right;display:block;)Right Cell 23%%
|%%(text-align:left;display:block;)left%% |%%(text-align:center;display:block;)center%% |%%(text-align:right;color:red;display:block;)combine alignment and color%% 

produces this

Left Heading Center Heading Right Heading
Left Cell 11 Center Cell 12 Right Cell 13
Left Cell 21 Center Cell 22 (longer for illustration) Right Cell 23
left center combine alignment and color