A screen will be displayed as shown in the following image. You do not normally need to change the other settings. At the summit this will usually be Kauwa. To specify other dates and directories see the following section. There is now a flag identifying new data.
Warning messages are informational only.
Pointing to a specific flat can also be useful. The data reduction recipes can be cpu-intensive. Use the sub-array where possible. It will help if you use a different machine for things like Netscape, email, etc.