Irises get given several name but your irises (I. Germanica) grow from a rhizome and are probably Bearded, they're also known as Flag Iris or German Iris.
There are several heights and lots of different colours but what most of them thrive in is full sun and a poor soil.
You can get some that require a wet/boggy soil too, some that are Beardless aswell.
There are irises that flower at different times of year.
I'm guessing that your germanica type will flower in the spring-early summer.
I grow a lot of Iris Germanica and love them :-)

Have you ordered them as pot grown plants or as rhizomes ?

Most germanicas bloom in late spring, and early summer, though some can repeat bloom in late summer and fall, too. Planting them as late as Oct./Nov. will probably keep them from blooming in 2011, so you may have to wait for 2012 for bloom. Generally, plant them where they will get at least 1/2 day of direct sun, in well-drained soil. Leave the to 1/2 cm of the rhizome showing, with the fan of leaves pointin up, and the leafy end pointing in the direction you want it to grow. If your soil is poor and sandy, I would give it tomato food 2-3 times while it is leafy, and water occasionally if there is drought. After bloom, cut the flower stems down to the base, without damaging the new leaves. After 3-5 years, you will probably need to dig up and divide the rhizomes to keep them vigorous and flowering. Normally very easy and hardy, so don't worry over them!