You will need to pay interest, this can be negotiated with the person providing the loan and depending on in which timeframe you can pay the loan back.
You probably will have to provide how you are going to pay back the loan within the timeframe of the loan.
You can also take a look at websites specialized in BTC loans like BTCJam.
I have 6 million dogecoin..
Those 6 million dogecoin should get you a loan for about 1.8 BTC.
You will probably need to get the rest somewhere else like BTCJam.
Make a post here saying you want to loan 1.8 BTC (or less), say that you have 6 million dogecoin as collateral (120%)
Provide how much interest you can pay to the person giving you the loan and when you can pay the loan + interest back. Also probably provide how you intend to pay the loan back (job, mining, whatever).
It's probably the safest if you send the collateral to a trusted escrow unless the person giving you the loan is very trustworthy.