[AC Question]

I have only had my Samsung Galaxy J3 6 for about 1 month, so I'm still learning about it. I have put 2 vidoes from my desktop computer onto the phone successfully, I don't think I have tried pictures yet until just now. I plugged the phone into the computer, tapped allow access, and opened the phone on the computer as a storage device. I made 4 folders on the SD card from the computer, then started adding pictures, all JPEGs I think. I had seen the computer show the pictures I put on the phone while I'm transferring them. With the phone still plugged in I check the pictures from the phone from the my files app, and the first 4 folders show correctly. I think I started by opening a file I did not put anything in, and I saw about 6-10 files with the same name (%%%%%%%%%.%%%). The other files contained both folders I didn't put there and several files each all with gibberish names made from letters numbers and symbols, and none would open. I unplug it and check again, and it shows the same. I plug back into the computer and the computer shows gibberish also. Both the computer and phone take a long time to open folders as if it has to decipher the files into the gibberish I see. I decide to try the gallery app and see my pictures there except almost all are solid grey, some mostly grey with a little picture in them, some perfectly fine, and one looked good from the picture list, but goes all grey except for a streak of color when I try to view it.

What did I do wrong, how do I put pictures on the phone from the computer? I have pictures of what I see if I can figure out how to upload them to the question area here.