¿Has plantado las flores?
Compramos los zapatos
He buscado la información en el red.
ANSWERS
¿Las has plantado?
Los compramos
La he buscado en el red
EXPLANATION.
The noun which is the direct object of the verb (the one which is receiving the action) is the one which has to be replaced with a pronoun. The pronouns go before the verb, even when there are two parts to the verb, and we can pick the right pronoun depending on the gender of the noun. (refer to pronouns table)
Then, we can see that "las flores" would be replaces with "las", "los zapatos" replaced with "los" and "la información" with "la".