You have to use some or all of the 6 numbers given to calculate the target value (shown just above the 6 numbers). You can add, multiply, subtract and divide. So, for example, if the 6 random numbers are 1,3,8,10,25 and 30 with a target of 301, you could multiply 10 by 30 and then add 1. To do 10 x 30, click the 10, then click the X symbol and then click the 30. As you click, they change colour. The 2 selected numbers are then replaced by the result of 300. You'd then click on the 300, then click the + symbol and then the 1. Your target is achieved and you can move to the next challenge.
To move to the next challenge, click a grey, starred tab just above the text that says 'Combine these numbers to hit the target '. A new target and available digits is displayed.....repeat!
Here's my effort for 31 August ( to share your effort, you need to click the arrow icon located just above the last challenge's tab- this will copy your result to the clipboard and you can then paste it into any textbox):