The Metro Home Screen has an All Apps tile. Click it and scroll to find Google PlayStore.
Click the PlayStore tile.
You can search by clicking in the top white area. Or you can choose Categories and search from there.
Click Categories to see what is on offer.
You can browse to find the App you want. I use Google to do preliminary research. The best photo gallery App which also permits exclusion of unwanted image folders - is QuickPic.
To open a Search box click on the "magnifier" at top right.
Begin typing in the name of the App ... and suggestions appear. Click on the suggested QuickPic.
I outline The App we want in a red box. Click it and we learn about it and can download it.
Click Install to download and install.
Before installation, you must agree with the requirements of this App. Click Accept.
Download progress is shown.
When download and installation is complete you have the option of Opening the App (or Uninstalling).
The first time you Open QuickPic you get the option of obtaining "Free Cloud Space" but you must then give your details. Avoid by clicking the Skip option at top right.
QuickPic opens with tiles named from folders in which there are images. QuickPic goes through all the storage in the Minix to find these folders. See here to use QuickPic to show only the photos you wish to show.