As I discussed in an earlier SRM 101 post, you should create all your required Site Columns before putting your Content Types together. (Obviously, given the evolving nature of any organization’s metadata requirements, you will almost certainly have to come back and create new Site Columns and alter your Content Types.)
To create a Site Column, login as someone with Administrator privileges and click on Site Actions > Site Settings > Modify All Site Settings.
Under the Galleries column, select ‘Site columns’. (Duh.)
In the Site Column Gallery, click on ‘Create’.
For the new Site Column, enter the column’s name and select the type of information in the column.
To simplify managing all your columns, it is a good idea to bunch them into groups. Either select an existing group or create a new one.
Next, you can enter a brief description of the column, determine if the column is mandatory or optional, limit the column’s length and create a default value.
Click ‘OK’ and you will return to the Site Column Gallery where you will see your newly created column.
That’s it. Now your new Site Column will be available for use in your Content Types.
