What is an infinitive verb and how do I conjugate one?

An infinitive verb is the most simple form of the verb that has not been adjusted to explain who is doing the action, but simply any action itself. In English, the infinitive verb will always begin with "To", for example; "To eat", "To live" or "To jump" and to conjugate these verbs in the first person present tense, you would simply change them to "I eat", "I live" and "I jump".
In Spanish, an infinitive verb will always end in -AR, -ER or -IR, for example; "comer" (To eat), "vivir" (To live) and "saltar" (To jump). In order to change an infinitive verb to the first person present tense, generally, you remove the ending (-ar, -er or -ir) and replace it with an "o" to result in "como" (I eat), "vivo" (I live) and "salto" (I jump).