Press the plus button at the top of the expenses list. Then fill out the description, amount and date fields. You can also add an image by pressing the image icon on the top right. Now select one or more payers, who paid the expense. It is possible to split it by different amounts. For example, someone paid 60$ and somebody else paid 20$.

Next select the persons between whom the expense is split. Here you can also set the amount for each person individually.