Ok so lets make it clear you want to be a lender and your capital is 0.1 and tou want the borrower to pay 50% interest for 1 week loan?

Much better to post what kind of collateral do you accept if thera any takers, then set your own rules and prove that you have that amount by showing that you realy have it. Lastly, you as a newbie should not hold the collateral, let trusted ones handle that.