I know you want that valve on your car but... If the flange is different & it vents to atmosphere along with the tone of your questions if the stock one is working clean it up (crush it if you feel comfortable doing so, I'll get to that) & put it back till you have a better handle on what it is you are doing. you will want to replace the gasket as well.
crushing a valve: the stock valve can hold a fair amount of boost by putting it in a vise & gently crushing it till the vacuum hose just touches the body of the valve. this increases the spring pressure of the valve & will help it hold a higher boost level. do not go all ape on it you'll ruin the valve.
If you just have to vent to atmosphere & be all fast & furious (read; slow & frustrated) you need a gm style blow through mas or a change over to speed density. if you have to ask about these you are not ready to do either.
Installing a blow off valve is quite straight forward but you do need to do some research before you introduce a huge vacuum or boost leak into your car & risk big time motor damage.
Like was stated before spend some time looking at other peoples set ups, go to the manufacturers website & study the installation instructions. ask someone with actual knowledge (whop can be there in person) to help guide you. don't be insulted by any of this, none of us were born with the knowledge & had to learn, I'm just saying by error is an unnecessary & painful method in this case.