Help loosen tight curls

I'd love to loosen my tight curly hair, but NOT straighten it. I just bought Phytodefrisant and have not tried it yet. Does someone know the best way to apply it? Should I apply it with another styling product (Sebastian Control Top gel, KMS Hair Play moulding paste, Wella Energy Styler volumizing mousse)??? Also how often can I apply it considering I wash my hair only twice a week. By the way, I am white, Eastern Europe descent...I have fine hair (but alot of it!), cut in long layers, just past my shoulders. Thanks.