The first you have to open this page. Then press New issue button. After it do the following actions:
You can do it the same as a bug report. BTW: It's better to discuss (for example here) a new enhancement before creating a corresponding issue.
You can also email me when you want to report a bug or advise an enhancement. In this case I will create an issue by my own.
Note: due to Yandex mail filters it's better to include the library's name in your letter's subject such as shown below: