Before adding a farm please check out our article on Farm vs Block's to determine which is the best option for you and your enterprise. 

From the Web App, select the Account tab from the left navigation panel.

Select Farm Management.

Click Add Farm and fill out your farm details.

Once you have finished, press Save to create your farm.

From the Menu tab, select Switch Farm.

Select the farm you wish to switch to from the drop-down list.

Click on the arrow to the right of your Farm Name.

Select the Farm that you wish to switch to from the drop-down list.