How do you check how many games you owned and the total value of those games on this website?

I suppose you're referring to these:
https://www.steamgifts.com/account/settings/profile
https://www.steamgifts.com/stats/personal/steam

You could just go to your profile by clicking on your image on top corner, and by hovering your mouse on your gifts won, you can see that value

Welcome to SG.
When the question is resolved, please click on OPEN in the upper right and set it to CLOSE.

Guidelines
FAQ
Comment Formatting
Once you read it, it is variously easy. Enjoy.

I'm pretty daft usually but the only way I've known is to manually start creating a giveaway and plunk the game name into the search bar, fill in some random info and then click into the "review" part of the giveaway and it will tell you (something similar):

"You should receive X$ CV for this giveaway"

If you were to check for the games you currently OWN, then your games list on your steam profile is the easiest way.

your steam games

And then you can also check the "Bundled Games" list for games that have been bundled before and therefore have reduced CV.

For all I know, I didn't answer your questions at all...