I've spent the better part of the last decade in sales related jobs with consistent success, and landed interviews for positions way above my qualifications and experience (unfortunately I couldn't talk my way past my inexperience :).
When you follow up with a company after you submit your information, talk to whoever answers like a normal person - like your buddy or girlfriend, just more professional. Write down what you're going to say ahead of time as a guide. Something like this would work well:
"Hi, my name is [blah], I'm hoping you could help me out for a second?"
They will say "sure!" or "Of course!" or "I hate you" (Just kidding, I've never heard anything negative after asking for 'help').
Then say "I submitted my information to your firm/company/agency in response to an opportunity in your marketing/sales/IT/operations/finance/accounting divison, and I'm wondering who I would talk to about this opportunity?"
They'll give you the name and contact information for the right person.
It's that simple.
The advantage to asking for the specific division is: They may give you the hiring manager for that department instead of the human resources generalist, which potentially puts you a step ahead of the process.