When there are two verbs in a row, conjugate the first and leave the second verb in the infinitive form. So, you might know how to say quiero—I want. If you want to do something, like rent a car, you’ll say, Quiero rentar un carro. This is just the I (yo) form, and there are five + conjugations for first, second, and third persons. That is an issue for the verb conjugation lesson, however, this will help you form sentences that have a bit more depth. In order to ask someone if they want to do something, the first verb form would have to be in the tú or usted form (for you), but any verb directly after must remain in its infinitive form. ¿Quieres (tú) tomar algo?/Do you want to have something to drink? ¿Quiere ir conmigo usted?/Do you want to go with me?
Auxiliary verb structures are a great place to start when you are trying to take all that hard earned vocabulary and put it into real sentences. Here are some familiar ones that may help you easily start forming sentences and get out of the fear bubble of speaking Spanish in real life. For the sake of practicality, I’ve just provided the yo and the usted forms of the first (auxiliary) verb.