Hi all! This should be helpful to all chemists, since it's not posssible to use tags in order to display molecular structures. It's a little bit complicated. For formulas, you could use 'tex' tags, and also, 'sub' and 'sup' tags. But, unfortunately, for now is not possible to display structures on forum. You could do it by uploading pictures. There is a useful chemistry graphical software, which is free and could be used for design and modeling. First is JChemPaint which is software that creates 2D chemical diagrams. JChemPaint Next two are 3D molecule viewers: JMol and Gabedit. Useful could be also Chemistry Development Kit, which is actually programming software. It's available here. I hope this would be useful for the start. Cheers!