Hi,
You can configure Load Balancing on the ASA from ASA 9.4.x onwards:-
http://www.cisco.com/c/en/us/td/docs/security/asa/asa94/configuration/general/asa-general-cli/route-policy-based.html
Also refer these for ASA codes before:-
https://supportforums.cisco.com/document/59986/loadbalancing-dual-isp-asa
https://supportforums.cisco.com/document/49756/asapix-load-balancing-between-two-isp-options
Thanks and Regards,
Vibhor Amrodia