Where clause in select statement was represented by 2 properties: 

1. WhereClauseText, this is the string representation, you can fetch or set where clause directly by using this property.
2. WhereClause, which is type of TLzCustomExpression, this property includes detailed information about where clause. Please check "How to use expression" for more.

You can check following demos shipped together with this component to find out more information about how to work with expression

1. visitexpression