My best "go to" vegan meal is spaghetti squash...you can bulk it up with mushrooms, olives, tomatoes...anything you're in the mood for.
You do really have to learn a lot before just diving into vegetarianism...you will need B vitamins for sure, as they are very hard to get in sufficient quantities without red meat...
On the brighter side...hardened arteries will actually heal themselves with a proper vegetarian diet, so don't give up. It's not hard to do, you just need to know what you're doing. Maybe an on line group could help you, I'm sure there are some out there.