KEYWORD ( CONDITION )
{  # begining of block of code to exec marked by {

   # stuff you want to do goes in here

}  # end of block of code to exec marked by }

##</code><code>##

if ( $some_condition ) {
    # some_condition is true
    while( @something && @something_else ) {
        shift @something;
        pop @something_else;
    }
}
else {
    print "Some condition is false!\n";
}