Practical example of how to build a footer in Lightning Web Component and inserting a call to action within it
<div slot="footer">
<lightning-button
variant="neutral"
label="Cancel"
onclick={handleCancel}
></lightning-button>
<lightning-button
variant="brand"
label="Save"
onclick={handleSave}
></lightning-button>
</div>
Read also Tab for LWC in Salesforce