This guide will let you know how to Find Steam ID.
1- First, you have to launch the Steam app, then click on View on the top of your screen and go to settings. From the settings, you have to click on the interface on the left side of your screen and make sure that the “Display Steam URL address bar when available” is checkmarked.
2- After this, click on Ok and close the settings window. You have to click on the arrow next to your profile on the top right side of your screen to view the drop-down menu and then click on View profile.
3- On your profile page, you can see your steam Id URL on the top of your screen. Then you have to click on the edit profile button.
4- On this page, you have a custom URL field. You have to scroll down and then click on the Save button.