Your dashboard already shows your visitors without any of this. These are for when you want your numbers in Google's or Meta's own tools: Analytics for a fuller picture, the Meta pixel to measure ads, and Search Console to see what people searched before they found you.
You only ever paste the ID. If you paste a whole block of code, Kitset keeps the ID out of it and throws the rest away, so nothing you paste can break your site. The tags go onto every page, and the Analytics and pixel ones load a moment after the page, so they do not slow it down.
One thing to know: once you add Analytics or a pixel, your site is tracking people with tools that are not ours. Whether you need a cookie notice for that is your call, and the common questions page says more.
Step by step
Open Connections in your dashboard and find "Tools that track this site".
Press Connect on the one you want.
Google Analytics: paste the Measurement ID, which starts with G-.
It is in Google Analytics under Admin, then Data streams. Old IDs starting with UA- no longer work at Google and are refused.
Meta pixel: paste the pixel ID, which is a long number from Meta Events Manager.
Search Console: choose "HTML tag" as the way to verify, then paste the whole tag or just the code from it.
Wait a minute after saving, then press Verify in Search Console.
Save. It goes onto your pages straight away.
If it does not go to plan
It says that did not look like a Google Analytics ID.
Use the ID starting G- (or GT-), not your account number and not an old UA- one. Copy it from Admin, then Data streams, then your website.
Meta says my pixel is not detected.
Check the ID in your dashboard matches the pixel in your Ads Manager. Some people have more than one pixel and connect the wrong one. Then visit your own site once and check again.
Search Console will not verify.
Give it a minute after saving, and make sure you chose "HTML tag" in Search Console. Verifying by DNS works too, at your registrar, without this.
How do I change one?
Press Manage on that row, then "Save new one" with the new ID, or Remove.