It depends on the conjugation. Let’s have a look step by step:
1. “-ar, -er, -ir” is dropped and the following endings must be added. This process is similar with all regular verbs.
A) First conjugation “-ar”: o, as, a, amos, áis, an
El / Ella ama
Nosotros / as amamos
Vosotros / as amáis
Ellos / as aman
B) Second conjugation “-er”: o, es, e, emos, éis, en
El / Ella come
Nosotros / as comemos
Vosotros / as coméis
Ellos / as comen
C) Third conjugation “-ir”: o, es, e, imos, ís, en
IRREGULAR VERBS: Irregular verbs share conjugation regular endings, except in first person singular which is irregular. This first person singular may determine the new verbal root that verbal forms will follow. But, there are irregular verbs which present irregular forms in first and second person singular without following any regular path. This fact implies learning by heart Spanish Irregular Verbs. For example:
(This verb follows first conjugation endings, although it finishes in -"ir")
El / Ella va
Nosotros /as vamos
Vosotros / as vais
(Verb "ser" is probably the most irregular one in Spanish)
1. Present Indicative is used to talk about habitual actions. For example:
George va a la escuela todos los días.
George goes to school everyday.
2. When we talk about a near future, present indicative is used. For example:
Tom juega al futbol esta tarde.
Tom is playing football this afternoon
A near future can be said in English using present continuous, but not in Spanish.
3. Scientific or universal truth. For example:
El sol sale por el este / El agua hierve a 100 grados.
The sun rises in the east / Water boils at a hundred degrees.