Learn Swedish: Jag var förkyld igår. - I had a cold yesterday.

In English, we usually say that we have a cold. In Swedish, however, förkyld is an adjective that describes your condition. You literally say "I was cold-sick" (jag var förkyld) rather than using the verb for "had" (hade).

Is var just the past tense of är?

Yes! The dictionary form (infinitive) of the verb "to be" is vara. In the present tense, it becomes är (am/is/are), and in the past tense it becomes var (was/were). Remember that Swedish verbs don't change based on who is doing the action, so it is jag var (I was), du var (you were), vi var (we were), etc.

How would the sentence change if I wanted to say "We had a cold yesterday"?

Because förkyld is an adjective describing the subject, it has to match the subject in number. If you change "I" (jag) to "we" (vi), you must add an -a to the end of the adjective to make it plural: Vi var förkylda igår.

Can I put igår (yesterday) at the beginning of the sentence?