First make sure that you have the antenna connected to the RF jack. Go to the Home screen of the TV and select the Antenna TV tile on the right hand side of the screen. (If you acquired the TV from a previous owner, they could have hidden this tile. See the steps preceded by Otherwise.) If this is the first time you scanned for channels, just follow the onscreen prompts (including setting your time zone). Otherwise, go to Settings (below Home in the left column on the home screen) > TV Inputs > Antenna TV > Scan again for Channels > Start finding channels. Use the arrow keys to navigate the menus/tiles and press OK to enter. To save, make sure to select Done and press OK.
The manual for the Hisense Roku TV (2019), 32HF4030F is available here: https://www.hisense-usa.com/support/models/32H4030F_hd-hisense-roku-tv-2019
. The current link to the manual is https://assets.hisense-usa.com/assets/ProductDownloads/88/c8c9a74079/Roku-User-Manual.pdf
. The section for setting up TV channels starts on page 39 of the manual. See the section starting on page 10 for information on using the remote or TV front panel buttons in the menu.
I hope this helps.