Here are some solutions you can use to create videos by adding music to a photo. If you're on a desktop or laptop, you can use a web based solution like Audiogram29 to create videos completely within your browser, or you can use a video editing suite like Adobe Premier Pro87. Video editing software typically has a learning curve to get up and running, and can be overkill for the task at hand.
Audiogram29 is a free application that runs in your browser. You start by uploading your music, and selecting a portion of the audio file to use in your video. From there you'll be brought to a screen where you can upload your photo to use as a background, choose the size and layout of your video (square, landscape or portrait), and optionally add text and waveforms as needed.
No technical knowledge is required, simply follow the instructions on screen to create professional looking videos.
If you're working from a mobile phone, there are many different options for apps on both iOS and Android which can create a video from a photo and audio file. Note that you'll need to have both your photo and audio file saved and accessible on your device. Listed below are some options for apps for mobile devices: