I have maxed out the 4GB of internal memory. Was told to purchase a Sim Card.

Check to see that you did not get too large a card for the phone. Your manual will tell you the limits you have to abide by.

You need to manually move the files in the phone to the 64GB card.

There is an app called "My Files" (depending on the operating system you have) it should be something like this:
1) Open My Files App.
2) Locate and tap "Device storage" under the "Local storage" section.
3) Locate, tap and hold on the folder/file you would like to move to the new card.
4) Locate and tap the menu button, depending on the device, it may look like 3 dots at the top right of the screen. - Some phones have menu button on the opposite side of the back button.
5) Locate and tap "Move", this should bring you to a screen where you can pick "SD card" which is the 64GB you bought.
6) Tap on "SD card" and finally locate and tap "MOVE HERE" to begin the transfer.

This is how you free up memory on the device using the card you purchased, the phone *should* move all new picture you take with your camera(phone camera) to your new 64GB card automatically.

Please tell me if you need me to clarify something.
-Mike