Sometimes searching with your keyword and the term, "icon" will help you get more transparent image results.
To take photos of yourself or your learning, use Google Slides. There's no need to use other online apps or filters.
Successful designers always iterate. This means making lots of versions of a design and seeking feedback to improve with each version.
Need a large, top quality image to print on a big poster or use as a desktop wallpaper?
In Google Images, go to 'tools' then use the 'size' menu to select 'large'.