Q.) How Did Existance Come Into Existance?
A.) You spelled Existence wrong and to make a long story short, our senses are not capable of answering this question yet.
Quote (Wikipedia)
In common usage, existence is the world of which we are aware through our senses, but in philosophy the word has a more specialized meaning, and is often contrasted with essence. Philosophers investigate questions such as "What exists?" "How do we know?" "To what extent are the senses a reliable guide to existence?" "What is the meaning, if any, of assertions of the existence of categories, ideas, and abstractions."
The word "existence" comes from the Latin word existere meaning "to appear," "to arise," "to become," or "to be," but literally, it means "to stand out" (ex- being the Latin prefix for "out" added to the Latin verb stare, meaning "to stand").
The word 'exist' is certainly a grammatical predicate, but philosophers have long disputed whether it is also a logical predicate. Some philosophers claim that it predicates something, and has the same meaning as 'is real', 'has being', 'is found in reality', 'is in the real world' and so on. Other philosophers deny that existence is logically a predicate, and claim that it is merely what is asserted by the etymologically distinct verb 'is', and that all statements containing the predicate 'exists' can be reduced to statements that do not use this predicate. For example, 'A Four-leaved clover exists.' can be rephrased as 'There is a clover with four leaves.'
This philosophical question is an old one, and has been discussed and argued over by philosophers from Parmenides, Plato, Aristotle, through Avicenna, Aquinas, Scotus, Hume, Kant, Kierkegaard and many others.
In mathematical logic existence is a quantifier, the "existential quantifier", symbolized by ∃, a backwards capital E. To symbolize "Four leaf clovers exist," mathematicians would first define predicates, P(x) = "x is a clover" and Q(x) = "x has four leaves", and then form the well-formed formula (∃x)(P(x) and Q(x)).
For the question of why the universe exists in the first place see Cosmogony.
http://en.wikipedia.org/wiki/Cosmogony :
Cosmogony, or cosmogeny, is any theory concerning the coming into existence or origin of the universe, or about how reality came to be. The word comes from the Greek κοσμογονία (or κοσμογενία), from κόσμος "cosmos, the world", and the root of γί(γ)νομαι / γέγονα "to be born, come about". In the specialized context of space science and astronomy, the term refers to theories of creation of (and study of) the Solar System.
Cosmogony can be distinguished from cosmology, which studies the universe at large and throughout its existence, and which technically does not inquire directly into the source of its origins. There is some ambiguity between the two terms; for example, the cosmological argument from theology regarding the existence of God is technically an appeal to cosmogonical rather than cosmological ideas. In practice, there is a scientific distinction between cosmological and cosmogonical ideas. Physical cosmology is the science that attempts to explain all observations relevant to the development and characteristics of the universe as a whole. Questions regarding why the universe behaves in such a way have been described by physicists and cosmologists as being extra-scientific, though speculations are made from a variety of perspectives that include extrapolation of scientific theories to untested regimes and philosophical or religious ideas.
Attempts to create a naturalistic cosmogony are subject to two separate limitations. One is based in the philosophy of science and the epistemological constraints of science itself, especially with regards to whether scientific inquiry can ask questions of "why" the universe exists. Another more pragmatic problem is that there is no physical model that can explain the earliest moments of the universe's existence (Planck time) because of a lack of a consistent theory of quantum gravity.