Hiya
Showing appreciation is when another member of the site 'thanks you', or shows your appreciation. This could be for support, ((Hugs)), advice etc. The number of appreciation you have will go up as more people thank you. You won't be able to see the Thank You! button under your name as you can't thank yourself, but you will on the profiles of others.
I have thanked you today so you should see a '1' beside Showing Appreciation now
As for the donation, you are correct. A thank you message will show at the top right of the screen
This message changes when the next person donates.
Hope that makes sense. And thank you for donating