Go to a money lending website and check the loan offers they have

If your question is how do I calculate interest on a loan, then the simplest answer is an effective interest rate calculator. Other than that, there are formulas available to do it in your home.
P = A/ {[(1+R) N]-1}/[R (1+R) N] is the formula where A is the total loan amount of yours, P is the periodic interest rate with credit, N is the number of payments you need to repay to your lender.
You can do this simple math at home or you can just choose an online calculator to count it down for you. In most cases using a calculator gives you the right amount without flaws and all you need to do is to put the digits there.
Go to a money lending website and check the loan offers they have
Choose the loan you want and type the amount in the checkbox
After that use the calculator to calculate the Effective Interest Rate