So I am reading the rulebook of magic the gathering. I haven't played it but I am curious about the game. In the rule book, I didn't see how much mana you start off with. For example Naga Vitalist.
If you have one forest land card on the field can you summon her? My understanding was that you had to have 2 land cards on the field since she requires two mana. Do you start off with a certain number and type of mana in your mana pool? How much mana does a land produce and how is that determined?
Mana is an abstract resource produced by abilities and spell[1], though most commonly by the intrinsic activated abilities of basic lands (e.g. Forest).
305.6. The basic land types are Plains, Island, Swamp, Mountain, and Forest. [...] A land with a basic land type has the intrinsic ability “{T}: Add [mana symbol],” even if the text box doesn’t actually contain that text or the object has no text box. For Plains, [mana symbol] is {W}; for Islands, {U}; for Swamps, {B}; for Mountains, {R}; and for Forests, {G}. [...]
This means that every Forest has an ability that produces one green mana at the cost of tapping the Forest.
I say "green mana" instead of just "mana" because mana comes in each of the five colors, and it can also be colorless.
Naga Vitalist's mana cost consists of 1 green mana and 1 generic mana. The generic mana cost can be met by paying mana of any color or colorless mana. So, to be able to cast Naga Vitalist, you will need to produce this much mana (e.g. by using the intrinsic abilities of two Forest).
"Mana pool" refers to the mana you have produced but not yet used. It empties at the end of each step and phase, so you can't carry mana you produce on in turn into the next (for example).
You can read more about it here.
In the rule book I didn't see how much mana you start off with.
You do not start with any mana, or even any means to obtain mana. You will need to play lands first.
My understanding was that you had to have 2 land cards on the field since she requires two mana.
Basically, yes, though they need to be untapped.
Do you start off with a certain number and type of mana in your mana pool?
No. In fact, it's constantly being emptied. Mana basically need to be produced immediately when needed.
How much mana does a land produce and how is that determined?
Each basic land produces one colored mana (white for Plains, blue for Islands, green for Forest, red for Mountains, black for Swamps) by tapping it.
No, you don't start with any mana at all. The way you get mana is by casting spells or activating abilities which make mana for you.
By far the most common way of making mana is by tapping a land. For example, a Forest (on the battlefield, not in your hand or library or anywhere else) has an ability that says
{T}: Add {G} to your mana pool.
Here "{T}" stands for "tap this permanent" and "{G}" stands for one green mana. It's a little confusing because most Forest cards don't have this ability written on them, but if you look at an old Forest you'll see it written out explicitly. With newer lands, though, you just have to remember that any land which has the subtype "Forest" (check on the type line in the middle of the card) has that ability, even if it doesn't say so on the card. The same goes for other basic land types, but with other colors: Mountain (red), Island (blue), Plains (white), Swamp (black), and Wastes (colorless).
There are many other lands, and most of them have their own mana-producing abilities, but they will typically say so on the card itself.
Many other permanents that are not lands can also produce mana. Naga Vitalist itself is one example, although you do have to get her on to the battlefield first, and for that, as you noticed, you will need two mana, one green and one which can be any color. The most common way to do this is by having two lands in play, but if you find some way to make two mana (one being green) without having two lands, that's a perfectly fine way to pay Naga Vitalist's cost.
Though it is no longer printed on the cards, all lands with a basic land type have the ability to tap for one mana, determined by the type for that land. So Islands tap for 1 blue, Swamps tap for 1 black. Nonbasic lands don't always tap for mana, but most do, and those that do either have a basic land type, like Breeding Pool, which gives them the abilities of that basic type, or say how they make mana, like Simic Guildgate.
Your mana pool is empty at the start of each step and phase of each turn, unless an effect stops it from emptying, like Omnath, Locus of Mana, or gives you mana, like Frontier Siege, at the start of a step or phase of the turn.
And there are other ways to make mana, besides using lands. Birds of Paradise is one of the more famous examples of a creature that taps for mana, there are also artifacts that tap for mana, like Sol Ring, rituals that cost mana to cast but give you more back Dark Ritual and a few cards that create mana in other ways like Channel and Elvish Spirit Guide.
