Two ways are possible.
The first is to download on your smartphone one of the many applications concerning storage and subsequent use on the ground to follow the right track without going wrong. There are many of them, some of which can be downloaded from Google Play (Endomondo, Wikiloc only as an example). These applications allow you to upload files for free but, when you use them to follow a track, they ask for payments.
An application currently completely free of charge is OruxMaps, to download it you need to go to the website with the same name.
An excellent guide in Italian on the use of this application can be found at this link:
Alternatively, a more in-depth guide at this link:
The second tool necessarily requires the possession of a Google account and consists in using Google Maps; at the moment, to download the desired routes, you need to access from a computer since the possibility to create your own maps is not present for smartphones, while then it will be from your own device that you will be able to follow the track when you will be on site.
Step by step, the necessary actions for the purpose:
First of all download the desired tracks from this site on your computer, then open Google Maps and click on the menu at the top left (left of the space where you can type the place to search).
The following window opens:
Among the four options (Tagged – Saved – Visited – Maps) click on Maps
At the bottom you find and click on Create map
On the open window you find and click on Import
Now you have only to click on Select a file from your computer and you can enter the desired track on Google Maps.
Then just open this application from your device, open My Places and then Maps to have the track well evident on your screen. Following the easy instructions, you can use your device to follow the route and go for your walk.