Left click (normal click) an emoji to copy it to clipboard.
Paste this into Discord and send, if you have embed perms it will appear as an emoji.
To add an emoji:
Find an emoji on discord and right click it
Then press copy link (on desktop).
On Browser click the emoji and then right click the pop up and press copy image link.
Paste this link into the bar at the top that says "Enter image URL or data here".
To favourite an emoji:
Press the star icon and press the emojis you want to favourite,
favouriting emojis stops them from being hidden by other emojis such as packs
Press Edit -> Delete and then click on the emojis you want to delete to delete.
To add a pack, press packs and click the pack you want.