We can break down the sentence into smaller sections: I bought; a laptop; new; on Saturday. "I bought" is a verb (a doing word). To write a verb correctly, we need to change it to reflect the person doing the action and to reflect when the action happens. Step 1: what is the Spanish word for "to buy"? Comprar. Step 2: Who is it buying the laptop? I. Step 3: When did the action happen? In the past, one time. Step 4: Change "comprar" to the past tense, I form. Compré. What is the Spanish word for a laptop? Un portatil. What is the Spanish word for new? Nuev(o/a). "New" is an adjective, which changes depending on the noun that it describes. The noun here is the laptop. The laptop is a male and singular noun. So we use the adjective "nuevo". Remember that the adjective always goes before the noun, even though we need to check the noun first. On Saturday is translated into "en sábado". Let's put this together: Compré un nuevo portatil en sábado.