Weebly supports Calendly's embed options including inline, pop-up text and pop-up widget. Sign in to Weebly and select Edit Site. Under the Build tab, select the page that you'd like to edit and use the Basic toolbar on the lefthand side. Locate the option to add an embed code, and drag it into position on the page.
Edit the custom HTML within the box and paste the embed code that you copied from your Calendly account and publish the changes to your website.