Issues with forum Width & Transparency

[Kahina]

This is my first time posting anything so I apologize if I put this in the wrong thread.

My issues:
1) I am working to embedd my forum into my group's website. So far we can get the table (catergories and topics) to fit in but there is still the edging from the forum. Essentially we would like to make it so that viewers can vertically scroll but won't have to horizontally scroll. Below I've included a link to our webpage and the forum that we are trying to work with.

2) I would like to make the table background more transparent but I can not locate where to change the opacity in the CSS for it. If someone could point me in the right direction that would be awesome.

Any assistance would be greatly appreciated.:3