From your course homepage, click the Content tab from the navbar.

From your contents page, find the module you want to add the quicklink in. This could be either a already created module or you can create a new module.

From within the module you want to edit, find the item you want to add the quicklink in and click on it. From within the HTML editor click on the icon that shows a chain. When hovering over it you will see that it says Insert Quicklinks

From the Insert Quicklinks table you are going to find the item you want to add. For this example it will be an assignment

Once you find the assignment you want to add, click on it

Once clicked, the link to the assignment will automatically appear in the HTML editor.

Click Update or Save and Close and the link will be placed in that area for students to access.