To invoke the zclient, enter the following from the directory to which you copied the files "zclient.spec" and "zclient.tcl"
The initial zclient window should appear allowing you to select a server name and then select a database (e.g. Cranfield). The Query window will then appear and you can enter keywords.
Since Cranfield is a collection of articles about aeronautical topics, choose appropriate keywords (e.g. wing, laminar, helicopter,...).
Click on the HELP button in any window for information about the use of that window.