Need A Vector Drawing App? This One's Free And Simple. [1]
When it comes to editing and designing images on a computer, there are 2 fundamental types of software available. The first type is based around a bitmap, where the image is composed of thousands or millions of individually coloured dots or pixels. Photographs are bitmaps, so any program that lets you edit photos is a bitmap editor.
If you draw a red line across the middle of a bitmap, 5 pixels wide, then you now have a few thousand red pixels that are totally unrelated to each other.
The other type of picture is what's known as a vector image. Instead of being a collection of pixels, it consists of a collection of lines and curves. If you draw that same red line in a vector-editing program, the line is a single object. You can pick it up and move it. You can drag its corners to make it shorter or longer, thicker or thinner. Each time you adjust it, the line gets redrawn using the required pixels.
Vector-based images can be very complex if required, containing thousands of lines and curves and fills. But underneath, it's a series of objects rather than pixels, so it's very easy to edit anything without disturbing the other objects.
If you have never used a vector image editor, there are a couple of great examples that are available for free. One of this is from Microsoft. It's called Expression Design, and formed part of a software suite for web designers which Microsoft stopped supporting in 2010 and then decided to give away for free. You can still download it, and it works just fine in Windows 10.
You'll find it at https://www.microsoft.com/en-gb/download/details.aspx?id=36180 [3] as a 48 MB download. It's malware-free according to VirusTotal and Web of Trust.