The "loan" you made to the S corporation is not an expense. The expense(s) come into play when that money is spent by the S corporation.
What you need to do is record that loan on the books of the S corporation; the balance sheet. The entry would be to DR. Cash and Cr. Loan Shareholder.
You should also charge the S corporation interest for the use of the funds. Any interest paid by the S corporation would be an expense for the S corporation and interest income on your personal tax return. If you don't have a note between the corporation and you with an interest rate, then the IRS could take the position that this is not a loan but in fact a capital contribution. Probably not significant since you are the only shareholder and most likely have always been an S corporation. It would be cleaner with a note and interest.