Injecting Auto Orders In Client Terminal

Hello,

This is my first post in Tuts4you. I have watched I learn some basic techniques from Lena Cracking Tutorial. I am doing some experiment on Stock Market Client Application to extend his feature through OLE. But I am little unsure about which part of reverse engineering I have to use or learn.

I am looking to send background orders in client application without running macros (Mouse Clicks,Keyboard Strokes). Here is picture (Buy.jpeg) for buy order when sent from client application (After Pressing Of "F1" Key) :

For normal circumstances I have to fill Total Qty & Price section from keyboard stroke, Click on send button. This will place orders in exchange. But running macros won't help because it blocks me from using other application at the time of macros running. That is why i want to send this order directly as background process without affecting other application work. I need help on which part of section of reverse engineering I should learn which have same example that I wish accomplish in above example.

Thank You