Once signed into Acquire, select the Menu, or 'hamburger' button that looks like this:
Add a item by hitting the 'plus' icon (#2)
You will now be able to add item information here. (Asterisk-*- is required information). Once this is done, you can select the 'save' icon on the top right.
You can also add a picture of the item for easy reference as well. To add an image saved from the device's memory, select the 'Open Gallery' button, which will allow you to add this.