To assign a value to a variable use ":="
line 1 should read:
tStr := 'UPDATE People SET zActive = 0, zEmailAddr = "help@amazon.com" WHERE zID = 6;' ;
Also notice the semicolon that is outside the final single quote. Without this the program would fail to compile.
I am assuming the database you are using accepts a pair of double quotes to delimit strings as the one I work with uses single quotes.