How do you get the money from an online loan?

I'm about to get a loan online from lendingtree.com and was wondering how they give you the money. I know that it's wired to my account, but how do they know my account? Do I have to give them the account number or do they already know from my social security number? I wanted to wire it into my sister's account and was wondering how I would do that. Thanks

be very careful they use your bank account to deposit and withdraw money...