Well, yes, if you're using a regular verb. Some are irregular verbs, like lesen, which means "to read." In a lexicon, if you look up a verb, you look it up by the infinitive in German. If, after the infinitive, you see a different-looking form in parentheses, that's the "du"-form -- the 2nd person singular form. You use that to help you figure out the third-person singular conjugation -- everything else is the same. After lesen, you would see (liest). The conjugation would be: ich lese, du liest, er liest, wir lesen, ihr lest, sie/Sie lesen.
For the verb "to be" (sein), it's completely irregular. The conjugation (which just needs to be memorized -- there's no way around it) is: ich bin, du bist, er ist, wir sind, ihr seid, sie/Sie sind.