can i use a YYJ Darkmagic for 5A and can u guys upload some 5A tutorials
Yes, you can. On the learning section of this website you’ve plenty of 5A tutorials to get you started at 
Good luck
Any 1A yoyo will work fine for 5A. They also have my favorite section if tutorials in the Yoyofactory 5A May tutorials.
When it comes to starting 5A then make sure to study the counterweight to yo-yo ratio. That is crucial because if it’s off-balance then your tricks won’t go as smooth. A DM is a heavy yo-yo so use a heavier CW. Then head on over the 5A section, 5A may, Yoyoskills 5a Tuts on youtube, or check out basic mounts on Miguel Correa’s youtube: themiggymigs.
7:1 ratio.