Wanting something: が ほしい
たい is for an action. ほしい is for something you want.

Learn
Use noun + が + ほしい for a thing you want: 車 が ほしい です means “I want a car.” The noun comes before が ほしい. To say you want to perform an action, use the verb’s たい form instead.
English “want” is a verb, but ほしい is an i-adjective. Learn が with this basic pattern rather than copying English object grammar. You may also see は when the desired thing is the topic or is being contrasted, as in the money example below.
Its forms follow the i-adjective pattern: ほしくない です means “do not want,” and ほしかった です means “wanted.” As with たい, start by using it for your own wishes and questions to the listener.
Examples
私 は 車 が ほしい です。
I want a car.
時間 が ほしい です。
I want time.
お金 は ほしくない です。
I don’t want money.
何 が ほしい です か。
What do you want?