To export your project, click File > Export Project.

The Export Project window will be opened.

Your file name will be prefilled, based on the project name. If you want to change it, you can do so in the File Name section.
You can select the type of file you would like to export. You can select between PDF, PNG, and TIFF.

You can choose to preserve a transparent background if your design has one. If this is unchecked, your exported file will have a white background.
You can adjust the width and height of the exported file.
You can adjust the DPI that the exported file will have.
Once you have confirmed all the export settings, click Export.
Note that each export has a credit cost associated with it, which will be displayed on the Export button.