If this is the First Trust Deed you wish to invest in. The Title (Escrow) company or the MLB will provide you the escrow instructions and
all the documents signed by the borrower including the promissory note.
Make sure the loan terms such as the interest rate, duration, prepayment penalty clause, etc. are to your satisfaction.
The Title company will provide you the instruction to wire your money. In the case there are multiple lenders, each lender will wire the money separately to the title company.
When the title company receives all the lenders' money, the lenders' names will be recorded to the county recorder's office and you will receive your monthly interest payment until the loan maturation date or when the borrower pays off the loan early.