A candidate may donate cash to their own campaign. For example, when the campaign opens a bank account, the bank requires a deposit. A candidate may use their own funds to do that. If the campaign wants the option to pay the candidate back, enter it as a loan by the candidate to the campaign. 
Open the ORCA campaign, and click on Transactions, then Loans, then Cash Loan. Fill out this screen:

Put the candidate name into the Lender Name field. Start typing the candidate’s name and let it auto-fill. If the program prompts you to enter an address for the candidate, stop. The software may be trying to create a second contact for the candidate, which will cause problems. 

If the candidate will be on the primary ballot and the loan is made before the primary, choose Primary in the Election field. (Remember: if the candidate is on the primary ballot, any money reported for the general election can’t be spent until after primary election day.)
Interest rate, due date, and check number are optional. Leave the repayment schedule as “As funds become available,” unless there’s a different arrangement. 

The Carry Forward Loans box is for a loan carried over from a previous campaign. When the campaign makes a payment on the loan, or the candidate decides to forgive some or all of the loan, go back to this screen to enter that information.
For the campaign to pay back the loan, there must be a loan agreement. You can find an example here. Make a paper loan agreement and keep it with the campaign ledger.

The campaign may pay the candidate back up to $6,000 in loans for the primary, if the candidate is on the primary ballot, and another $6,000 for the general election. If the candidate loans the campaign more than that for the election, then it’s really a contribution.