pressing add media and searching for altervista. But they are very recent so they won't show in the description. You need to copy the one you want.
After a while you can search in add media. In this case as there are no more icons is not problem but if you want to search by my icons you can add by:linux-rules that would be interesting if you want to search a icon of a software that if you search in the add media you will find a lot of icons that they are not related with the icon. For example, lets imagine that there is a software called landscape. If you search "landscape" the first results will be landscapes that are not connected with the program.
hope is clear