Shortly after sunset, as the sky starts to get dark, look to the southwest (the sun sets in the west, so look to the left of where the sun set). You should see two very bright "stars". They're the brightest things in the sky at that time of night, so there's no mistaking them with other stars. If you don't see them, maybe the sky is too bright -- check again in another 15 minutes or so.
The brighter of the two, which is closer to the point where the sun set, is Venus. Jupiter is a little higher and further away from the sunset.
If you watch these two planets over the next month, even if you just glance up once every few days, you can actually see them moving closer together in the sky. If you've never noticed the planets moving before, this is a great chance! By the end of the month, the two planets will be really close together (as viewed from Earth; they'll be hundreds of millions of miles apart in reality).
Even though I am a professional astronomer, I love to watch the planets dance together like this. It makes it easy for all of us to actually see the motions of things in outer space. And you don't need any special equipment -- just look up shortly after sunset.