There should be adapters out there for your specific camera. This allows you to attach the camera to the scope, and then your ready to rock.
Try Bintel, or Astro Optical Supplies, or just about any dealer of scopes and accessories.
They will help you.
does your achromat take 2" eye pieces? what you'll want for starters is a K mount T adapter, this attaches to your camera in place of a lens, and presents a female T thread. then a 2" to T-thread camera adapter which screws into the previously mentioned K mount T adapter, giving your DSLR a 2" nose piece the same as a 2" EP.
From there you may be sweet, however I've not used a DSLR with a refractor. you may also need an extention tube to achieve focus.. I dont know for sure, But somebody here will... sit tight and wait for more replies.
The aforementioned adapters can be bought from bintel, myastroshop or any of the online stores, expect to pay between $35 - $50 per item.
If you get the Kmount - T adapter you may not need anything else as Alex says. Check the 1.25" adapter that fits in your 2" focuser. If it has a thread on the end then that will screw into the adapter. However you will get strong vignetting with it. To reduce this I would suggest getting an Orion (or similar) Prime Focus adapter. It has a much larger bore and will give less vignetting. Plus you can screw 2" filters into the end of it if you want to.
Thanks Eric great help !! exactly what I though the 2" adapter reduces vignetting I assume, now that should cover prime focus but what adapter do should I buy for eyepiece projection.