No you don't. Sexual stimulation is not a need like eating, drinking, or breathing. Nobody has ever died of sexual abstinence. There's a TED talk and a peer reviewed 2014 study in the sticky which talk about sexual addiction, which may well be the reason why you think that fapping is a need.
How long do I have to do this for??
That depends on what your goal is. If you believe that masturbation is morally wrong or unhealthy in any amount, you may want to do nofap forever. Maybe you just wanna do it for a month-long challenge like many people do. Maybe you believe that porn addiction has your brain all fucked up and you'd like to cure yourself of that but you'd like to go back to fapping in moderation after that, in which case most people will tell you to do nofap for 90 days. Don't worry if one month to 90 days to forever seems like a long time; everyone who does this agrees that it gets easier as time goes on.
Is this related to that reddit thing?
Not in the slightest. This board was made as a result of nofap threads on /pol/. This board has absolutely nothing to do with either the reddit nofap community or the for-profit corporation Nofap LLC which runs it. It is the board owner's belief that profiting off of porn addictions is unethical and that attempting to copyright memes such as "nofap" is retarded.
Calm down nigga. Breathe deep. Don't open that new tab. Get your hand out of your pants and spread your legs so they're not touching your dick. All right. Do you really wanna fuck up your streak man? Do you really wanna throw away all the progress you've made? Even if you've only been at this for one day, progress is progress. Even if you fucked up yesterday, you don't have to fuck up now. You're not some little bitch who can't say no; you're a real human being who can choose what he does. Don't fuck that up bro. You'll only regret it. You know damned well you'll only regret it. You fucking know what a piece of shit you feel like after you fap. And you know you're more likely to fap again if you do it now. And again, and again. It doesn't have to be that way, but you know it likely will be if you fap now. Is that what you want? To feel like a piece of shit day after day? You're not a piece of shit. You can resist bro. We're all gonna make it.