VB-6 Rpt Designer in Data Environment

I am running VB6 with SP5. How can you include a variable in the SELECT statement (SQL) which appears on the CommandText property line of the DE Command? The objective is to select records for printing based on criteria the user inputs on a form. Normally, you could code it in a procedure using the ASCII CHR(34) for string variables or CHR(35) for dates within the SELECT statement command string.

Also, in the properties of the DE Command, what is the function of the Parameters tab? The documentation on this is not very useful.