Can I grow cannabis? How do I obtain cannabis to grow?

Yes!  You can!  If you live in Colorado, you can even do it legally!  According to our fine state laws, anyways.  No matter how much space you have available, no matter what your situation, there is a method of cannabis cultivation you can use.  Modern advances in LED and CFL lighting have created a pool of technology from which any person can cultivate at least a small amount of cannabis for personal use.  There are many resources available for setting up grow rooms and spaces, and I would rather direct you towards those, but if you think you have a particularly difficult space or situation, I would be glad to offer my direct input.  I would personally direct you towards this fantastic book that every cannabis cultivator should read.

Once your cultivation environment set up, you will need to determine how you want to obtain your cannabis plants.  There are basically two ways to start, you can either obtain clones (small vegetative plants cut from a {usually} proven female) or you can obtain seeds.  While some people (who seem to all work for dispensaries) will try to warn people away from buying seeds, this is actually my preferred cultivation method.  It is difficult to verify the quality and genetic lineage of clones, especially as our current MMJ environment has led to a grotesque proliferation of unscrupulous business practices.  Most of the best clones I have obtained have been through contacts in the cultivation scene, rather than through dispensaries.  Dispensaries have given me powdery mildew, spider mites, thrips, and a ton of clones that were either accidentally or intentionally mislabeled.  Cannabis seeds are very easily obtained through the magic of the internets, and there are at least five very reliable seed banks that you can order from that will ship discreetly to the United States.  Risk is minimal (worst case you will not get your seeds, and most seed banks offer a guaranteed shipping method in which they will reship in case of customs interference) and you know exactly what genetics you are getting.  The other mitigating factor is time, as growing from seed will usually put you two-three weeks behind growing from clone, for your first cycle.  After that, you can certainly keep clones from your plants, and only obtain additional seed as you desire more variety in your garden.  Seeds or clones, there are positive and negative factors associated with both, and it is really a matter of preference if you have ready access to clones.  If not, however, then one of the many internet seed banks can help you in getting set up with your chronic.