There are two options to insert your own HTML, CSS or JavaScript code in the head or body of your website:
After «signing in to the Designer» you will land on the home page of the Designer Editor, which is the area called «Site editor». From here on you will have to proceed as follows:
There is a button with a dropdown icon in the blue bar on the top of the page labeled with the currently showing page in the editor (on screenshot: «Home Page»).
Open the «Pages and folders» pop-up by clicking that dropdown button. Now click on the «<> Site scripts» link at the bottom to add a general script which is active for the entire website.
Insert the code into one of the two input fields, depending on where you want the system to place your scripts (head or body). These scripts will be active on the entire website.
Open the «Pages and folders» pop-up by clicking that dropdown button. To add a page-specific script click on the «3 dot icon» on the right side of the concerning page and then on «Edit page scripts».
Insert the code into one of the two input fields, depending on where you want the system to place your scripts on the page (head or body). These scripts will be ONLY active on the specific page you put them on.