Start up the trusty notepad in Windows and type up your table the way you want it to appear in plain text - using spaces to arrange the columns. Then press <Ctrl A> then <Ctrl C>
Back in your Accyweb post, click "Go advanced" if you aren't already using that feature. Above your text, in the row of formatting symbols, there's a hash button second from right. When you click it, it'll put
[code][/code]
at the point where your cursor is flashing.
Move your cursor back to the adjacent square brackets at the middle and press <Ctrl V>
Good luck