1. Click on the 'More' button found within your Text box
2. Select 'Insert table' in order to add a table to your SharePoint page.
3. You are able to change your Table styles, insert and/or delete any columns or rows and align your table. It is also possible to modify your table if you right-click the table inside your Text area.
(Note: This current version of SharePoint doesn't allow you to merge any cells within the website and to do so you would be required to format your table properly in Microsoft Word. Copy pasting from your formatted table from Microsoft Word onto SharePoint would solve this issue.