How do I access the SD card slot on my n iPad 10th gen?

I WAS TOLD BY BEST BUY I CAN USE A SD CARD IN MY TEN GEN IPAD FOR SOME WHAT REASON I CANT FIND THE DOOR TO IT . PLEASE TELL ME IF THERE IN CORRECT THANKS AND HOW DO I CLEAR UP STORAGE THAT I DONT USE ANY MORE IF NEEDED THANKS

[Re-Titled by Moderator]

Original Title: SD card