The V7 Plus sports a microSD memory card reader. If your laptop or personal computer can also read that card format (Most notebooks are so-equipped), you should be able to transfer music files
The V7 Plus is a smartphone. Most smartphones should let you save any mp3 song available online by touching and holding your finger on it and selecting 'save.' Once a music file is stored on your library, touch-and-hold it and choose 'assign' in the contextual menu.
The Vivo V7+ is an Android smartphone and the Android market offers a bunch of free ringtone apps such as MP3 Ringtone Maker, Zedge and more.
Since your V7 Plus has a sound recorder (also known as 'voice memo'), a very simple technique involves simply placing your phone near your computer's speakers, playing whatever song, music or sound you'd like as a ringtone, and recording it -- you can even use your voice, your child's voice or even your cat's 'meow!' Record it with your mobile and 'voilà!' Unless that function was specifically blocked on the Vivo V7+, you should be able to navigate to the ringtones menu and assign that recording as a ringtone. Of course, the sound quality may not be ideal but, at least, it's free!
Here are links to some of the free ringtones (compatible with your Vivo V7+) we offer:
Free Horror Ringtones Free Tropical Ringtones Free Ringtones-a-gogo Free Techno Ringtones Hear All Our Free Polyphonic Ringtones