I commend you for considering opening up your marriage at your wife's request. It speaks volumes about your open-mindedness and willingness to see your wife happy. However, it should not be done at your expense! There is a lot of work and talking to do between the moment someone in a couple says "I want to open up our marriage" and the marriage actually becoming open. This is something that definitely should not be rushed. Some couples take a year or more of communicating and resolving issues before either of them ever actually has a date with anyone new.
If she wants additional relationships to add quality to her life and enhance her relationship with you, then it would behoove her to wait until so many, many things are discussed before she pursues/dates/has sex with anybody! One person announcing what they want, the other going to a website for a list of do's and don'ts, and a few therapy sessions is not enough preparation. There can be many many baby steps to take, you don't have to jump in right away just because she wants it. Wait until after the foundation of your marriage is solidified further and communication improved. You will both be grateful that you didn't rush headlong into a mess that you'll have to clean up later.
There is so much to read and learn before you make this fundamental change to the dynamic of your marriage. I suggest you both read Opening Up by Tristan Taormino; in fact, read it together. Go over the points the author discusses and use her lists for figuring out how you two will incorporate ethical non-monogamy into your lives.