First, congrats on finding an investor. Some of the steps will differ depending on whether you offered the investor equity or debt (a loan). If equity, the investor`s equity % should be specified in the articles of incorporation, assuming that you are incorporated somehow (and you should be, like LLC, C-corp, etc.). I would get those papers drawn up through a business lawyer. If it is a loan, you can use some standard loan documents or a lawyer could help there as well.
The money should go into a business bank account, and maybe the investor can do it in chunks as progress is made. You should supply the investor with financials, probably monthly, so he can see where the money is going.
I would strongly encourage you to get a lawyer to set this stuff up. Legal is not an area you want to skimp. This is your baby, your sweat and tears, and you don`t want someone taking it from you because details were not put in writing. The investor should want the same as well.
Best of luck,