Step 1 :Go to Setup 

Step 2 : Inventory 

Step 3 : Click on Manufacturer 

Step 4 : Click on ADD MANUFACTURER , 

You can Add manufacturer name and Manufacturer website as shown below.

Step 5 : If you wish to disable the manufacturer which is already added , Just slide the swtich on right handside of the manufacturer name as shown below 

Step 6 : If you wish to edit the name of the manufacturer and website address after adding, click on the edit option on the right handside as shown below and modify the details accordingly..