For adding a new type of feed you have to go to "Settings" menu and choose the option "Feed".
There you will be able to register all the different type of feeds you want to use in the "Component" screen. For registering a new feed, click on the "+" icon located in the upper right corner of the table and fill in the information of the feed, then click on the save icon. 
The next section of "Feed" menu is "Settings". Here you will decide which unit you want to use and the % of dry matter to apply. You can activate the option you want just by clicking, then the option will be shown in green. For the % of dry matter just write the number and click "Save".