automating search engine query

hello

I am  working on a client side solution of web searching. I would like to know how I can query another search engine (like yahoo or alta-vistla etc). I want my code in VC++ to automatically initiate a query in any search engine. I am using WinInet classes to access the web pages. I think that search engines use some sort of scripting to get the user input. can that process be automated? like can our PROGRAM write our required query in the search box and then somehow initiate the search? There are some search engines like www.ask.com that place the user queries on different search engines. how do they work? I'll be really greatful for any tip or suggestion.