Firstly, and least helpfully, this might be the wrong board. Maybe. I'm not entirely sure myself
More relevantly, there are a few ways. If you can find 3 other people to play, one of whom wants to try DMing, then you're set. it's worth asking, cause the kinds of people who would like to play is surprisingly varied once you pass the 'for geeks' stereotype.
Failing that, you could ask at a local tabletop gaming store - many - mostly in america, as far as i can tell, living in uk - run campaigns every so often, or have a list of local groups. There are also online communities that arrange groups (prefer my anonymity too much for that, personally) or online tabletops such as roll20.
If all else goes wrong, there're always play by post games in various forums, ours included. IMO they're best for absolute beginners, because there's enough time to go away and check the rules if you're unsure, but they go very slowly, so it's a matter of preference.
As for ruleset, there are many out there. However, DnD is probably easiest to to find a group for. DnD 5e has just been released, and it looks brilliant as well as less hack and slash focused, but on the other hand, most of the
3.5e material is available for free, which is a huge help (the 5e basic rules are free, and worth looking over, but perhaps not ideal if you have a newbie DM). It's more clearly set out in the PHB and DM's guide, but you can muddle thru without - depends on your spending power.
Starter set wise..... IMO, they aren't worth getting, with limited rulesets and a single adventure. On the other hand, I'm the kind of DM who prefers to make my own adventures, so it all depends. If you want a quick taste of DnD, and aren't prepared to acquire the necessary materials for a full game without prior knowledge, then the starter sets will give you that.