Select a location in partial shade with good drainage. Morning sun is preferred, but a location under a deciduous tree with bright light is OK. Contrary to popular belief, Helleborus are not shade plants, just shade tolerant. They resent root disturbance and will wilt severly if care is not exercised during transplanting. Prepare the planting area, with ammendments, if necessary and gently remove the pot and place it in the hole, tamp the soil around the root ball to remove air pockets, then water it in. I usually add 2-3 Tbsp. of Dolomitic lime as a top dressing around the plant, before watering, as my soil is clay and therefore, acidic. Add a layer of mulch 2-3 in. thick around the plant, leaving an air gap of one to two inches around the stems to prevent possible disease and insect infestation.
Wait until blooms fade, then add a slow release fertilizer per package directions. I often use Osmocote, 9-month, w/Minors, but have also used other brands, with a 15-15-15 ratio.
Once established, Helleborus are drought tolerant and can survive long periods without irrigation. They do not tolerate wet feet and will not bloom well, if at all, under low growing, evergreen shade.
Grab your shovel and head for the garden! and find that perfect place where they can be observed and enjoyed.
I grow 100's of them, encompassing about 14 species and dozens of named cultivars. They really brighten a Winter landscape, when little else is blooming.
Hope this helps and enjoy your wise purchase!
Rb

Rb,
You gave great advice except for the general comment about clay soil being acidic. This is does not hold true where I live. I have clay soil that lime loving plants do well in. I have to ajust for acidic plants.
Remy

remy....
Your clay soil is different from that found in the mid-Atlantic and SE states, from Western PA, south to the Gulf of MX and westward to the Grasslands, excluding the Miss. River embayment area. Our clay is in the Order Ultisols, sub-order Udults, which is a highly leached forest soil, deficient in Calcium(Ca), Magnesium(Mg) & Potassium(K) and is characterized by the presence of Iron(Fe) oxides, giving it a reddish or yellowish color. It is generally acidic and infertile and requires the addition of Lime and fertilizer to support agriculture.
I expect your clay soil is in the Order Alfisols, suborder Udalfs, only moderately leached, with high native fertility, that will support agriculture without the addition of primary elements.
I apologize for the apparent generality, but was trying to address only the soil composition found in this area.