Learn Spanish (Latin America): Nosotros siempre usamos la computadora grande.

Usamos comes from the regular -ar verb usar (to use). Because the subject is nosotros (we), you drop the -ar ending from usar and add the "we" ending -amos, giving you usamos.

Do I have to include nosotros at the beginning of the sentence?

No, you can simply say Siempre usamos la computadora grande. Because the ending -amos in usamos already tells us the subject is "we," the word nosotros is optional and is mostly used for emphasis.

Why does the word siempre (always) go before the verb?

In Spanish, words that tell you how often something happens, like siempre (always) and nunca (never), usually go directly before the verb they are describing.

Why is it computadora grande instead of grande computadora?

Unlike English, where the describing word comes first (big computer), Spanish adjectives usually come right after the noun they describe. So, it translates word-for-word as "the computer big."