"I want to buy this yellow cap."
Translation:Quiero comprar esta gorra amarilla.
I'm not sure, but my guess is because there are some words in spanish that can be either gender. I think it's varies on the region. I was very confused because both la refrigeradora and el refrigerador, and el sartén and la sartén were counted as correct, until someone informed me both are used.
Just use "quiero". If you want to say "I want to" do something, just follow "quiero" with the infinitive of the verb for whatever you want to do. For example, "I want to travel" is "quiero viajar", and "I want to go to France" is "quiero ir a Francia".
We haven't really done things that would use "quiero que", which is followed by a subjunctive in sentences like "I want you to study more", which would be "quiero que estudies más". That's pretty advanced stuff, so for the kinds of sentences we have been working with, don't use "quiero que".