The expenses you refer to would be business expenses and would be deductible on Schedule C of your return. To enter them, click on the Income & Expenses tab of your return. Click on the Edit/Add/Review button next to Self-employment income and expenses. After you've entered the information about your business and entered your income from this activity and Continue (or you can "Skip for now"), you'll see the screen What kind of expenses did you have for XXXXXXX. Scroll down the list of expenses and click on the types of expenses you have and Continue. The program will then guide you through entering them.
The specific expenses you mention (I assume expenses like campground/park access fees, etc.) can be entered as "Other miscellaneous expenses" under "Less common expenses". You'd also be entitled to claim deductions for vehicle expenses and meals you incurred for business as well as additional expenses considered "ordinary and necessary" for you to conduct your business.