Questions about Demonstrative Pronouns:
Q: Why is it Éste es el carro que quiero and NOT Ésta es el carro que quiero?
Demonstrative pronouns must agree in gender and number with the noun they refer to or replace.
Q: Why is it le gusta aquél allí and NOT le gusta esté allí?
Demonstrative pronouns should be consistent with adverbs of place (aquí 'here', ahí 'there, close to hearer', allí 'there, far from both speaker and hearer') that accompany them. Because allí means 'over there', it does not make sense to use it with éste.
Q: Why is it me gusta este libro and NOT me gusta éste libro?
Use the determiner (without an accent) before nouns, rather than a pronoun.
Q: Why is it van a traer ése and NOT van a traer éso?
Remember the masculine singular forms do NOT end in -o. If you want to use the neuter form, do NOT use an accent.