The SciFinder structure/reaction editor can be slow (at least a minute) to load in your web browser, especially the first time you open it during that session. You may also be prompted to accept a certificate or ActiveX plug-in. More about browser requirements here.
A Java plug-in is also required for the editor. Most likely, this is already installed.
If you still have problems connecting to SciFinder, please contact Amy Prendergast. Sometimes this involves network or firewall issues, and you may need to work with your IT people to resolve these.