When we are developing sharepoint application its quiet common that we need to add site coloumns.So we can create our own cloumn for a share point list or document library or Content Type.Following steps will show how to create a site coloumn
Step 1. Goto to your sharepoint site and click on the site action menu (top right side)
Step 2.Click on the Site Setting Sub Menu.
Step 3.In Site settings page Go to Gallery Section and Click on Site Coloumn Link
Step 4.In Site Coloumn Gallary page you can see all the existing site coloumns.Next you have to click on the creat link in site coloumn gallery page.
Step 5.In site coloumn Create page specify the coloumn name you want to create
Step 6.Specify the type of Coloumn we are going to create.Here we are going to create a lookup coloumn.
Step 7.Specify the group under which this new site coloumn should go.You can add new group so it will help to identify the our coloumn.Give a meaning full busines group name or project name.
Step 8.Specify this will be a required coloumn.(suppose we added this coloumn into a list and saying this is required coloumn)
Step 9.Now we are going to specify our source list for theis lookup coloumn.Specify a list from the drop down.Look at my BlogHow to create list.
Step 10.Next we are going to specify which will be the coloumn in the source list being use as the source coloumn for this lookup coloumn.
Step 11.Specify this lookup coloumn supports mutiple value from the source coloumn.
Step 12.After sucessfull you will see the following screen, in which you can see the new cloumn created under a new group we specified.