Hi!
Once you have started, I.E. cqrlog is installed, opened and the log001 is created by cqrlog and you have opened it you will get the window "New QSO" open.
There just feed the callsign and other information and press ENTER or click "Save QSO " button.

Recommended reading: "New QSO/Help/Help index", or if you have not get so far you can access same help from this web page https://www.cqrlog.com/help/index.html