Bank Transfer

This is a payment for an already established Line of Credit (aka Loan) that you're making a payment to.  Or is this a new Line of Credit where they just put the money in you Checking Acct?

If you're just making a payment for an existing Loan where the Accounts are already set up in QBs, then you write the check for the Full Amount due this month.  You then enter a Split to show the amount of Principal which goes against the Liability Account for the Loan and then the Interest amount goes against the Interest Expense Act.

If this is new an you just got the money.  You need to set up two new Accounts, well, 3+, in the Chart of Accounts.  First give a little thought to the future.  Odds are you may have more Loans/Lines of Credits for future projects.  So I'd suggest looking to see if you happen to already have a "Loan(s)" Liability Acct.  If you do, we'll use it.  If not create a New "Loans" Acct and it will be a Liability Acct.

Under the Loans Acct create a Sub Account Named something to do with the Loan.  So maybe Chase Loan 12345 where the "12345 is the end of the loan number from the bank.  In the future you can Hide this Acct when you're done with it and open a new account with a specific name if you take out another Loan.

The money from the Bank goes into your Checking (or wherever) and is associated with this Loan Acct.  The Loan Acct (Chase Loan or whatever) will show your Liability owed).

Next create (if it does not exist) a Loan Expense Acct, where the type is obviously an Expense account.

When you make payments (as mentioned earlier) you'll Split the monthly payments against the Loan Acct to bring down the amount owed and the Loan Expense Acct to show your loan Interest.

If you make additional payments to bring down the Principal sooner, you would apply them to the Loan Acct to show the additional Principal Payments. 

Hope this answers your question.  If I'm way off base, send a little more info and we'll get you headed in the right direction.