@Natasha211
Hello Natasha, In fact you can charge a base price for one guest if you wish and then set a price that you wish to charge for each additional guest after that one!
I will include a couple of screenshots here for you to follow!
Firstly you need to set your Base price....in other words the price that will be displayed for your listing in a general search. This is how you do that!
On your listing editing page scroll across to 'Pricing' and you will see this screen....

Now once you have set that 'Base Price' scroll on down the page and you will come to a section called 'Extra Charges' and it is in this section that you include a cleaning fee and the additional amount you wish to charge for each guest after minimum number you have set.....one in your case......

Now when this is done....and remember to click 'Save Changes' when a guest puts their details and numbers into the booking part of your listing, these extra charges will automatically be displayed before they book.
I hope this helps you Natasha!
Cheers......Rob