The Process for Spouses in the US
The process for spouses already legally staying in the US is simpler, because much of the work of getting here and proving financial stability, etc. has already been done.
A spouse that is in the US already has permission to be here. That permission is temporary, so you will need to file to adjust the status of it. This is simply called an "Adjustment of Status." The permanent resident or citizen spouse still has to file a petition to sponsor his/her spouse, but this can be filed at the same time the adjustment is filed; there is no need to wait to file the adjustment. The process goes:
Spouses Outside the US
Spouses outside the US have a bit more work ahead, as it will not yet have been done.
If you have already been married outside the US, the process is as follows:
Once the petition is received, you can either wait for its approval and apply for the marriage visa, or use the K3 fiancée visa and then file an Adjustment of Status form I-485 (this can help get your spouse stateside faster, but the green card can be years coming through).
After approval and application, Consular Processing (direct application and interviewing) completes the process, and a decision will be made.
Get the Help You Need
Of course, a quick overview gives you a roadmap of the process, but there is much more that you need to know. Use the additional resources and USA marriage immigration visa information on this site and locate the professional services that will ensure an easier and more thorough, more successful green card application process.