I am assuming that your CM is more like a bush than a tree with clearly seen trunks? If so, it's an easy matter to change that, provided there are strong trunks in there - some of the more dwarf cultivars don't have a really strong skeleton and SHOULD stay as bushes, but if yours is about 6' tall, it should be able to be trimmed into a tree form. If it is in its first 2 years in the ground, I think I would leave it for another year, to grow a really strong root system the faster - more leaves = more energy = more roots. Maybe do a minimal trimming up the first year, and do more later.

In late winter/early spring, take a good look - from all sides - at the CM, and decide on which 3-5 trunks grow in a direction and form that will make a pleasing tree shape. You may have lots of trunks, and you may have only a few, it depends on how it has grown. Select the best ones - you can always let a sucker grow up later and replace one that isn't REALLY what you want. Start at the bottom, and trim off all the smaller stems/branches that aren't what you want - up to about 3-4' from the ground. Take out dead or crossing wood higher up, but don't be too quick to clear away too much from the top. If there are suckers growing from the base, try to pull them off, rather than cutting, as they will sprout out multiple new shoots from a cut surface. Once you have the most of the smaller stuff off, take another careful look, from all sides, and decide if you want to keep all the remaining trunks or only some of them - you shouldn't take off more than a quarter to a third of the leaf canopy at any one time, and it may be that you should stop there and do more next year. If you are in doubt about any branch, leave it, and come back to it later, since it can always be removed later, but mistaken cuts are GONE! As the CM grows taller, you can trim it up higher, but not too quickly.

You should follow the usual good pruning practices - use sharp tools; clippers for small cuts, loppers for bigger ones, and a pruning saw for big ones. Cut to the trunk or to a smaller diameter branch growing in the desired direction. Don't leave stubs. Keep your tools sharp.

crggrdener, thank you for the question! And dibbit, what a wonderful answer. I printed it out for reference next early spring.

I have a CM "forest" and tuned into the shrubs forum to see what could be done. I started working on the tree form last year and some are 8 ft. tall and very thickly spaced. So glad to know about not cutting suckers off. That's been my mistake all along.

Best to you -
Sunny