Loading platform

I am new to SolidWorks, presently using release 2011. I have made my first design attempt. I have had lots of problems with it. Firstly I could not add the fillet weld beads in the structure. I tried a lot without success. Then I decided to fake the welding beads at the external corners of the structure. The final appearance was not that bad but I disliked it. Lastly, I would like to add an appearance on the top plate of the platform so that it could be like a diamond aluminum plate. Could you help me with it?