Importing your own SVG icons into Iconly is easy: there's a button on the top right corner of every page that does just that.
Firstly, you need to login into your area via Github. When you click on that Import Icons button, you are directed to the Import page. Iconly considers these uploads as packages, so you may give it a name. This way you can refer to it later.
On the box below the name, you may add the SVG files from your computer. The box will show you a list of the files added so you can check before saving. Now click Save, and your package will be saved and accessible from any project page. This way you can add any icons to your projects.