Turn the mp3 player on by using the on/off switch. Turn you computer on. Use the usb cable that came with the mp3 player to connect the player to your computer. Wait for you computer to install and ask what you would like to do? Choose "View files" form there just drag and drop your music into the mp3 player's folders. If you computer does not ask you what you would like to do after connecting the player. Try disconnecting and turning the player off and on and trying again. If it does not work still try a different usb port and or restarting your computer. I had to unplug and re-plug 10 times for mine to work.
I'm sorry, I think you send your question to a wrong person. I'm not the seller. But I can answer for your question, I have bought a few of these mini clip MP3 player. Yes, you do need microSD card to store your songs and insert it into your MP3 players. in my experiences with these MP3 Players, the highest capacity for the microSD card can be used is 32GB, even it said handle up to 8GB only, but you can get away by using 32GB.
Try flipping the Micro-SD card upside down. If you're looking at the front (the part with the buttons), the card's electrical contacts should be facing you. If the card makes a click sound and stays in, than you're good to go. If you put in the the other way (with the label up), the card will not go in straight. If you still can't fit it in, than the unit may be defective and you might need to get another one. Good luck and I hope you get your player working!