Learn Spanish (Latin America): No tuvimos un asiento cómodo.

Tuvimos is the preterite (completed past) tense of tener (to have). Tener belongs to a special group of highly irregular verbs that change their stem to include a "u" in the past tense. The base changes from ten- to tuv-, and the "we" ending is -imos, giving us tuvimos.

The translation says "did not have", so why isn't there a word for "did" in Spanish?

Spanish does not use helping verbs like "do" or "did" to make sentences negative. To say "we did not have", you simply place no directly in front of the conjugated past tense verb to get no tuvimos.

Why does the adjective cómodo come after the noun asiento?

In Spanish, descriptive adjectives like cómodo (comfortable) almost always come right after the noun they describe (asiento). This is the exact opposite of English, where the adjective "comfortable" goes before the noun "seat".

Why does cómodo have an accent mark on the first "o"?

The word cómodo is pronounced with the spoken emphasis on the third-to-last syllable (có-mo-do). In Spanish spelling rules, any word with the stress on the third-to-last syllable automatically requires a written accent mark.