The ISIS collection of databases contains over 700,000 reactions. Although this is quite a lot, it is nowhere near comprehensive. It is good to use if you want to search for a type of reaction without being too specific about the exact substituents. The advantage over Beilstein is that searching is usually quite a lot faster. A Tutorial is available.
Accounts are available to everyone working in UK academic institutions.
The required software can all be downloaded once you have registered. Extensive Help files can be accessed from within the program and should be sufficient for anyone who wants to know more. Enter your Username in the box. Enter Password in the next box that opens. Double click on the main window.