Yes, easily. Once you have selected your desired invite template, click on the 'Media' tab on the left-hand side of the editor. From there, upload the desired image of the birthday girl using the 'Add Media' button, then drag the image onto the template.
From here, you can crop your image to ensure it fits within the boundaries of the template, or apply a filter to the image for decoration.
Absolutely, once you are satisfied with your invitation, just hit the blue 'Export' button in the top corner. If your invitation is a still image, select 'PNG', and the quality specifications you wish to export with. Higher quality files will look sharper, but may occupy slightly more storage. Lower quality files will take less time to download, but won't look quite as high definition.
You can. In fact, you can translate your invitation into any language, and it couldn't be easier. Just follow these steps: