Adding Nodes from another form...

I have some CCK types I have created for creating listings on our website. I have also created modules which allow people to submit a request for a listing on our site. These modules simply gather the information from a form and send it to us as an email. This is rather cumbersome as we then have to copy the information to the "create content" screen for that node type.

Basically, I need my module to be able to create these nodes and be able to add the location information to those nodes as well. Can someone point me in the right direction for how this is done within the database? Is there an API for node creation?

Thanks,